VOL 17 No.2 . AUG~1989 , ~ £ : : ~ . -: ~;~

BrUel & Kjcer ...Brilel&K}aefAuslra liaPty . L1d.

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Acoust ic Baffl es - afe easily installedafter co nstruct ion to provide economicalcontrol ct revertere nt noise -availablein a rangeof coverings.

For free and comprehensive technicaleervce . including a wide range oftechnical literature, contact the BradfordInsulalion otlice in your capital city.

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~~~~~ti~r~~~~g~~~ui~ti~~r ;~s~in~aller,Dr. Marshall HallUnderwater and Physical AcousticsDr.FergeFrickeArchitectural AcousticsProfessor Anita LawrenceNoise,llsEffectsandControlDr. RObertW.HarrisData Processing, Acoustic Emission

~~t~~~~~i~rib~~~~~ducers, VibrationDr. Neville H. FletcherMusical Acoustics, BioacousticsDr. Norman L. Carter:~~~~~ilg;,cal and Physiological

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~~~t~~t~~ ~~~t~~:\~~lslou~~~:ed by the(Incorporated in N.S.W.)Responsibility for the contents ofarliclesrestsupontheauthorsnottheAustralian Acoustical Society.Articles may be reproduced in fullprovided adequate reference Is quoted.

PrintedbyCronulla Printing Co. Pty. Ltd.,16 Cronulla Street, Cronulla 2230.Phone: (02)5235954. Fax: (02)5239637.ISSN0814·6039

August 1989

CONTENTS-====~~~=

Page

• Adding a Computer to Your Sound Level MeterRobert Cook .

• The Acoustic Properties of Wood in Relation toStringed Instruments

John Dunlop .

• A Violin Quality Assessment Method: Study IIGraham Caldersmith ..

• ACT Noise Control Ordinance SeminarJosephLai

• Activities in Department of Mechanical EngineeringDavid Bies

Publications by Australians ..

Front Cover: Sponsored by Bruel and Kjaer Australia Ply Ltd, showing theirrange of sound levef meters from a simple but accurate type for noise surveysto an advanced state-of-the-art instrument with interchangeable pfug-in applica-

~~; /::r~t~:e~:~:m~tf~:;~~~7:~tve range of acoustic investigations.

HEAD OFFICE: 24 Tepko Road, Terrey Hills, NSW 2084.Telephone: (02)4502066. Telex: 26246. Fax: (02)4502373.MELBOURNE OFFICE: 8/12 Pascoe Vale Road, Moonee Ponds, Vic 3039.Telephone: (03)3707666,3707166. Telex: 33728. Fax: (03)3700332.PERTH OFFICE: PO Box 7246, Cloisters Square, Perth, WA 6000.Telephone: (09)481 0189. Fax: (09)481 0193.QUEENSLAND OFFICE: PO Box 50, Brisbane General Hospital, Herston Q 4006.Telephone: (07)2525700. Fax: (07)2571370.

For more In/orm ation phone

THE CHADWICK GROUP

CIRRUS THE ECONOMICAL

RUGGED SOUND LEVEL METERS

• li ght, Conv en ientand Rugged

• LEO, SEL or SPLMeasure men t modeswitch selectab le

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availab le

• Ideal fo rMeasurem ent s ofLEO in the fie ld or inIhelab.

CHADGYP Roof Deck Systems provide:• Versatil ity of desig n . A monolithichigh sound transmission barri er _ Excel­lent sound absorption (partic ularly atlow frequency) _ Effect ive thermal insu­lation _ Speed of installa tion • Totalcomposite root and ceili ng system _ Firereslstance raUngs.

CHADGYPPOURED IN PLACE

GYPSUM,~=-; ROOF DECKS

CRl 2.J1A

.~ • Buitt in octa ve filte r

• L3M Microphoneco nnector fo r easychange ofmic rophone

• Fast, Slow , Impu lseresponse

• Accuracy to Type 1• AC, DCa nd

Computer outputsoplional

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Sydney (02)-428·8388 Mllibourne (03) 560·2422 Canbllrra (062) 80·6333

NEWS-------NSWMarch Technical Meeting

The first technical meeting of theNSW Division of the Society for 1989was held at NAL Chatswood on Tues­day, 21 March. Dr Harold Stanislaw,lecturer in psychology at the Universityof NSW, gave a talk entitled "What DoWe Hear When We Open Our Eyes?"Dr Stanislaw discussed "crossmodal"effects, in which stimulation of onesensory modality may affect perceptionin another sensory modality, and "atten­tional" effects whereby performancedeclines when observers attend toseveral sensory modalities, instead of

~~~t~~e';'e~~o~l~h~~s~~~~~ ~~n~~~~~=ing these effects. An application of thismethod suggested that when observersprocess simultaneous visual and audi­tory stimuli, "crossmodal effects areabsent, but severe attentional effectsmay be found". The talk was followedbya lively period of discussion andquestions.

April Technical MeetingOn 20 April Richard Heggie from

Richard Heggie Associates spoke on"Response of Structures to Vibration".

Over the past several years there hasbeen growing awareness of the need todevelop and refine criteria, standards

~~d vr~~~il~~O~Sn r~t~~~rur~~ t~~def~~~ti~occupants. Fundamental to these objec­tives is the requirement to have a clearunderstanding of the basic mechanismsat work, particularly those associatedwith ground/structure interface and the?~~~~~~e;~sponse of the structures

Richard Heggie Associates was re­cently commissioned by QueenslandUniversity to carry out a major researchstudy to review the current state ofknowledge regarding the response ofstructures to vibration from blastingvibration and overpressure. In parallelwith this study, the company has beenconducting wide ranging investigationsof the vibration effects on buildings andtheir occupants caused byroad and railtraffic, construction equipment, pile

~~i~;~~~ ~fd~itt~~~:o~achinery and other

Richard Heggie described findings of

~~:~ ~: :~~~eer s~~~~:rc~n~n~isi~~~sS~~gation.

WAMarch Technical Meeting

wa:h~eii~s~~e~h~~~~hm~~ti~~ ~~d~9~~Practice for Noise Control in the Work­place". This is a document producedby the Occupational Health, Safety andWelfare Commission of WA as a practi­cal working document for workplaceswhere there are noise hazards. It ex­plains the duties of employers, employ­ees, designers, suppliers, etc, under thenew Occupational Health, Safety and

Welfare Act and Regulations and givespractical strategies for complying.

The Code was presented by AndrewBaker and John Macpherson from theNoise Control Branch of the Depart­~ues~10~nd generated some lively dis-

A~~I Je~~~~~~~~t~:e~~~ble to tiethe April meeting in with a visit toPerth by Klaus Hojbjerg of the Brueland Kjaer Acoustics Group (Denmark)during his recent Australian tour. Fol­lowing his one-day seminar on "SoundIntensity, Principles and Practices"(attended by some members), Klausstayed onto present a condensedver­sion for the Society. A small but inter­ested group was introduced to theB&K type 4433 Sound Intensity Analy­~~~a~i~~sits application for a range of

Thanks to Klaus Hojbjergand LesSouthgate of Bruel and Kjaer for mak­ing the occasion possible.June Technical Meeting

Stephen Samuels of the AustralianResearch Board spoke at a meeting onJune20heldatTechnologyPark,Bent­ley. The main topic was the predictionof noise levels adjacent to signa Iisedintersections. This aspect of trafficnoise has not been adequatelyaddressed by standard methods suchas CORTN. The talk also covered a

~:~a1~d °r'es~~~~~ies of ARRB in road-

Conference NewsThe Organising Committee for the

1989 AAS Conference in Perth, Novem­ber23-24,announcesthatDrRagnarRylander, Professor in EnvironmentalHygiene at the University of Gothen­burg, Sweden, has tentatively acceptedan invilationto bea keynote speakerat the Conference. Dr Rylander is anauthority on the effects of noise onpeople. His presence is expected tohave a big impact on the Conferenceas he has a lotto offer uson the theme"Interior Noise Climates".

Further details: AAS 1989 Confer­ence, PO Box 7055, Cloisters Square,Perth, WA 2000. Tel: (09)4265700.

John Macpherson.

VICFebruary Technical Meeting

A symposium entitled "Traffic Noise- Whose Problem" was held by theVictoria Division at the Road Construc­tion Authority Theatrette, Kew, on 23February 1989. Technical papers werepresented by Stephen Samuels, RussellMatthews and Phil West, Chris Staple­ton and Stuart Mclachlan. The sym­posium was attended by approximately70 delegates.

April Technical MeetingThe April technical meeting was held

at the Bradford Insulation fibreglassmanufacturing plant at Nunawading.Fifteen members attended. The groupsaw, first-hand, the production of vari­ous fibreglass products from raw

materials such as sand and soda ashthrough to the finished products. Ashort technical presentation on theproperties of the products completedthe evening.

May Technical MeetingThe May Technical meeting was held

at the Royal Eye and Ear Hospital.Dr Peter Seligman discussed the devel­opment of the Cochlear Implant frominception in 1973 to the current daywith 1,700 patients who have nowreceived implants. The current implantgives approximately 30 per cent ofrecipients the ability to understandspeech without the aid of lip reading,while ail recipients claim some improve­ment in communication. This Australiandevelopment leads the world in coch­lear implant technology.

Acoustics and VibrationCentre in Canberra

The Acoustics and Vibration Centrewithin the Department of MechanicalEngineering at the UniversityCoilege,Australian Defence Force Academy,was formaily established in June 1988by the University of New South Wales.The current Director of the Centre isDr Joseph Lai,aSeniorLecturerintheDepartment of Mechanical Engineering.

The objectives of the Centre, relatingto the areas of acoustics and vibration,include co-ordination and developmentof research and education, undertakingcoilaborative work with other organisa­tions and provision of a consultingservice.

The Centre has a wide range ofmodern acoustics and vibration instru­mentation. The acoustics facilities in­clude an instrumentation laboratoryadjacent to an Anechoic Chamberwhich is of double shell construction tominimise extraneous noise and vibrationand which satisfies International Stan­dards for a lower cut-off frequency of150 Hz. The vibration facilities includea laboratory for vibration measurementsand analysis. State-of-the-art soundintensity measurements and modalanalysis of structures can be performedwith a dual channel, fast Fourier trans­form analyser together with a dedicatedmicro computer.

The Centre, via Unisearch Ltd,hasundertaken a number of consuiting pro­jects. With a view to undertaking largercommercial projects, the Centre hasrecently formed a joint venture, calledCanberra Acoustics, with two otheracoustics and vibration consultants inthe ACT region: Mark Eisner and Asso­ciates and Eric Taylor Acoustics.

As part of the Centre's continuing

:~~~~iO~ ~~~9~~~moe~ \~~ ~e;ireN~r;;Control Ordinance on It May 1989 andconducted a Workshop on the Basics ofNoise Control on 16-19 May 1989. Thefeedback from the Seminar and Work-

~~~~ fa;g~;~a~b~r~:sO~efhne v~~i6sos~iVibration Control will be conducted on

1989 AUSTRALIAN ACOUSTICAL SOCIETYCONFERENCE

DATE: 23 and 24 NOVEMBER, 1989VENUE: COTTESLOE BEACH RESORTTHEME: INTERIOR NOISE· CLIMATES

NEWS .•.

8th FASE Symposium onEnvironmental Acoustics

Inter-Noise 89 and SeminarThree hundred and five abstracts from

authors in 30 countries have been

~~I~~e~9, f~~e P1r~~~n~~~~~~atf~n~IN6~~:ference on Noise Control Engineering.INTER-NOISE 89 will be held in New-

b~~ 1~~~c~i ~al;~':~~iho~ ~6s~r?~se".;iinternational conferences on noise con­trol engineering which began in 1972.

The theme of INTER-NOISE 89 isEngineering for Environmental NoiseControl. Two Distinguished Lectureswill be presented at INTER-NOISE 89.DrLeoLBeranek,oneofthefoundersof Bolt and Newman Inc, will give the

~;~~~~~'6~i~~~r: f~~ ~hnevi~oonn~,,:~;,,~eNO~~~

Control", will concentrate on engineer-

~~secri~~~~ce~or ~~~~~~oranJirio~rc~~:head of the Graduate Program inAcoustics at the Pennsylvania State

~;~r~~~~tyT~~"t7i~eo ~:veh~ D~~~~g~;~D~~will be "Noise Control Applications ofSound Intensity". Professor Tichy willshow how advances in measurementtechnology allow engineers to followthe propagation of sound energy, deter­mine the sound power radiated fromlarge sources, measure sound transmls­sion loss and sound absorption coeffi-

;~eun~~ 7~~~n~~{;'U~~a~~~eu~~eO~~~~~I~~sound fields.

Thirteen special technical sessionshave been arranged for presentation atthe conference. Among the tOPiCSto becovered In the special sessions arenoise controJ around airports, interiorand exterior aircraft noise, barriers forhighway noise control, sound absorp­tive materials, sound intensity, andactive noise control.

Prior to INTER-NOISE 89 there willbe a three-day intensive seminar whichwill cover the latest techniques and themost recent advances in the use ofcomputational techniques for noise con­trol. The theme of the 1989 INCE Semi­nar will be Computational Methods forNoise Control. The increasing power ofdigital computers and digital instrumen­tation for noise measurement makesnew methods for the analysis of noiseproblems practical. During the first twodays of the Seminar, noise analysis andprediction methods will be discussed.~~~st~;~~~~is.will be devoted to noise

The topics covered in the INCE Semi­nar have been especially selected forthose individuals who wish to becomeknowledgeable of the principles under-

~~~~~~;d~~~~~~~~!:a~~r~~~~:~~~~;~~~~t~~S~ ;figs~~ni!'~n~:~;iiV. ~;: o~j~~~:ives of the Seminar are to develop anunderstanding of the underlying prin-

igi~~~~nZ~~:~h:I;:ar~~~[~~~~t~;~~~~!i:The Seminar starts at 08.30 on

Thursday, November 30, and concludeson the afternoon of Saturday, Decem­ber 2. One-day, two-day or three-dayoptions are available. The Seminar willbe taught by Professor RobertJ Bern­hard of Purdue University, ProfessorAndrew S Seybert of the University ofKentucky, Dr Jerome Manning of Cam­bridqe Collaborative, Inc, ProfessorPatricia Davies of Purdue University,and Dr David M Yeager of IBM.

Further in/ormation: Inter-Noise 89,PO Box 241;9 Ar/ington Branch, Pough­keepsie, NY 12603, U.S,A.

PeopleCongratulations

The degree of Master of Arts wasconferred on Campbell Steele, MAAS,

~~~~f~{:~~J:~~~~~New Members• Admissions

i~~¥;f;{Jf:;:hiffr~~~re~~~~~~~~l~mittee on Membership.New South Wales

MsL Hudson, MrPKarantonis, Mrl CRyan.

VictoriaMr S J Jenkins.

• GradedWe welcome the following new mem­

bers whose gradings have now beenapproved.

StudentMiss SWoon.

MemberNew South Wales

Mr L J Elliott (New Zealand), Dr J LGoldberg, Mr N I Oprya, Mrs S GReed, Dr S Thwaites.

VictoriaMr G R Campbell, Mr S J Jenkins.

Engineering Award

As~~~i~;:~u~~t;Ot~~i~oH~gDh~~ C~';;~i:n~~~Award as announced in Consulting

~n~~7:~~'nV~ :~~I~~:~i~;c;~r~e~o~9t~8~

~)~tf~~~~~J~~~~i;l~f~~~~tj~~~~1

Adding a Computer to your Sound Level MeterRobert CookAdvanced Acoustic al Technology Sectio nNational Acoust ic Laborato ries126 Greville St ree tChalswood N.5 .W. 2067

AB STRACT: By usin g a hand held compute, con trol the operation of 8 BrueIand KJeer Sound LevelMet llTtwe 2231, a flIl1100l data COilecrion system is achieved. Tha com purer SfOfl!$1h& da1810118te1printingor plotting of the IesullS and. via i ts in tertJc tive program , COIItroI&the sfllring up otthe SoundLBveIMater (SLM). TIle comptlter can stom and oulpul lfle results 01OM mirnJflIlogging penexJstaken wer 48 hours of measurtlmtlnls in its battery backed up m8lllOf}'.

INTRODUCTIONThe Advaoced Acoust ical Technolog)' Section at NALconducls research into noise measurement lechniques andhas lor many years provided acoustical advice andconducted measurements on a project basis for theDepartmen t 01 Defel'lC8. Increasingly tbese measurementshave concentrated on IhB environmental aspects 01 noise,partic ularly me annoyance caused by impulsiveSOllnd s Inthe residential areas surrounding firing ranges, detonalionsites, etc. The determi nation 01 the com mlln ity response 10impulsivenoi se of this type includest he measuremento l thepeak level of the impuise. The d8\lalopment ot thisSLMlcomputer syslem was an al1emPl to pl"OIIide a remceedata logging system utilising the e~ist ing Bruet and KjaerType 2231 Sound L!l\ff!1Maters already in use in the Section

The-aim was to p<ovidea system which· was nol too e~pansive to pu rcha se,

.was compaeta l'ld banery powered,• stored the measured values,• provided a means to pr int and plOC Ihe results obtained

versus time,• was control led by a real time clock to enable several

systems to be synchron ized. and· could be operated as a starod alone system, thus

parmittingmore datatobecollectedfor ag ivenn umberof start and also permitting the COllection 0' data ' romwith in the safety template areas surroundingdetonationS,et c.

By utilising a computer to slore the data, rather than justalta ching a printerlotheSLM ,l heda ta is available lor furtherprocessing bac k in the labofato ry. Toprint oot lip to 48 hoors01 data atone minute intervals in the held also resutts inprol!lemsolpaperstorage,elc .

The computer serectedwas t~ Sharp PC 1600, whIChhasavailablea printer/plolteraccessoryenda2.5 inch disc driveFig" re 1 shows the SLMkomplltel system. Also shown is thee~terna l batlery pack requ ired to e~tend the batlery lifeot l heSlM arld compu ter to 48 hours, Irl use, the equIpment isnoused in a self conteUled case whIch provides storage lorthe cal,bralion equipmen t, microphone. tripod , windscr&enetc. Figure 2 ShOWS me compu ter OlJtpult ing data to usprin terlplotter eee disc drive unit

FEATURES OF THE BRUEL AND KJAER2231 SOUND LEVEL METERThe 2231 SUd is a (I'9ital instrument Wllh liqClid crystal(I,splay. h is a 'o'8ry 'o'8rslltile Instrument capable 01pertorm ing mar»' ful1C1ions. lIs ope ratIon is controlled by anapplica tion programme. loaded into ils memory from anApplica tions Module inserted Into a socket on t~ rear panel

Figure 1

The Sl MlCompu ter System

on the instrClment. The same socket can hccse en InterlaceModule. which alloW!lthe output ofdataandthe controlling ofthe Sl M trent panel , S8\leral Appl icatioos Mod"l es are nowevaileble butt hisdescriptiorlwill beco nfined lo lh e use olt heSl M with lhe lnlegrating Sl M Module Type 8Z 7100 Withthis module installed Ihe main features 01the SLM are:

o Dynamic range 70 dB.o Aemole control and cce ranoe via the Interlace Modu!e

type Z19100I WH 2014 which is an interlace " similar '· tothe A$-232·C standard

Vol. 11 No. 2 33

F...... aCompuler. Printer!Plol1e' l nd lMk 00 ... UftIl.

• Compatible wi th 200 V, 28 V and 0 V poIariZll lion voltage

. ~= rneMufement 01 t.4AXP. PE AK INST,SPl. MAXl, MINL.LEQ, SEL

. P ra-set1a.b1e mea s.ule mflnl periodI lromonell8COOCl lo100 hours

o B' 11t1ry life 8 houl'$

FEATURES OF THE SHARP PC 1600COMPUTER AND ACCESSORIESThe Sharp PC 1600 CO!Tlp\lter is a poweffUl hancl lleldcomputei' that run, from lour 1.5 volt penlighl cella. Thecomputer nIlly be programmed in BASIC language andcomes equipped Wllh l6lc byIt1'S01 RAM .s stand a l'd Twoadditional RAM Modules may be insIa lled in the exparlSlOl'lsIolsonlhefllarpanelol lheinstrumentS-aJtypesolRAM loIodules.re Il'iaiIaDIe bulltle OM used he<e lealUreS32kbytesol RALl (c:ompIetlitwilh its(lWfl~eryb3ck~pl.

whic:hlMyblllXlf'lfogufedua RAU d«,.Thel'\alft lealuresal.,.,. PC 1600_:• Memoty eKP'ROabIe 108011t¥n.· Jnbuj,IlrNI ti.... doc..o lnbuil A5-232-c lIIlerface as .... as an opt oeaJ sen.I

iMertae..nclaneOghlbilanaloglod 'Q'tallnpulport- BatttotyW. 25 ho1.n..• Programmable in BASIC· Prrting .P'ld plcfl ong d dat8 in loul colours is~

us.>g .... CE·16OOF'Prinler.c.s.n. interface· Stor~ol datli and programs on 2!1 onch d<SC$ ut ing the

CE-16OOFDiac:Driveunil

THE PROGRAMTh<Jprogram 10 control me Sl M and manipulate t~e eeta0fX'-'Pies all of the lItlilldard 16k byte. 01RAM su pplle<!Wllhthe PC 1600 One additional 3211 byte M.mory Mod ule hasbeen insta lled and th is isconhgurO:ld to acl as. RAM disc.

The p' ogra m illsplilup inlo lwOaectlons: (lj sertingup,haSLM and gatharlng data and (2j pl'lnling. pIolt lng and storlOQthe data

SETTI NG UP THE SL M AND GATHERINGDATAWhel'l fJnl f\l lWllngtheprogfllm lh8 opeq1Ofeanenl8rtlleel' rr&nl clale and l lrle and deta.. or the~tltle

all<! mea5llremenl Ii 'e, Onee this has bMn completedinstroetions are sen' 10 the SLM to place it in the eorr.aol' tpul anet me"' ....,.rnenI modes pl'ior 10 measorernentsaetl' ally commencing , The opBfatof may now enter UlemellSllrement perioddestred {tImes from one minute to 5999minutesarepermilted).andlhede$lfedstal1lng hme.Alldthe~ ....mahOrl • stored in the Memory Mod ",1e 10~tMdf.ta

Whe<'lthe s&af1lng I".". lor the III'!ll me3SUrenMO (Il;Qn,

theeornputerremctely _ rtathe SLMand_ttslor 1heSLMIo d&/Mlf lhe fnt dala block . lhe end d lhe meuurtm<iltllperIOd, The cornout." DIfTlln8S lIS real t."a eIoel<, and • •.nen a new mlltute bagtna, l'e$8U the SLM and a newmeasuremenr~ tlIl.lSsynehroniling Ih8 _ 1101the rneastnmefIl:penodWlttlthe$tartolamlnute. This..-.thaI ... ..,...emsinllMall;haltirnewillrooasunrlhesame .-.u. Ourinog tile MO.I~......... penod theoornpu1el"Maml,* lha d8la and .i'anOYe'kBd isclfllaeted!he n it llauotablytaggec:l lor anentlOflwhenr....~ prinledorpIolted. The dllla ls th.... placfldin memorytogelherwith lheS1V1lflg limeol lhe measl' remenl

The measurement proceta econroes in Vii. wa~ "'nll l one 01thalollowing conditions OCClKll; (a) theopera,or rvll' .n. 10stop the program. (bj lhe.ystemlails dl' e to. IoW,baneryeon<Iltion or (c) tile llIOfagtl memory la fIl W, WhICheverCond ition occurs. the dll ta held in the Memory Module It

preserved b')'itsow nbalte ry back-upcireuit ry

Prinling. plott lng . nd . Ioring Ihe data.Thlee separate rOUIJnea allow Ihe data to be prinled,plolIed01 s10f8C1Of rem-d hom dose. Prinl,ng 01 piottlng d .asegmenl d the o-'a_ .-uuremenl • pruyided lor byspeei!ying the.u.rungand l inishingtimead851f«l

Figul8 3 showe an example of the pIoned output ,lrom1245 to 13« hou rs. derNed from a meil$l,lremenl penodoommencing at 1129 and ending al 1530 hou rs. F9Jre 4~lhepnnl«JOUlput lorthisperiod.lrJeISmafted\J"

¥·unoerranoe ~fromlhe Sl.M

FURTHER DEVELOPMENTSevetal modIl iCauona to !he 8lIist ing program could botperforme(I wtllCh WIll resull in imprtMlll1entS10 the syos,emAI.present l he progr.... has been wllnen lor the lntegrat~

SLM ApplIcallonI Mocklle BZ 7100 UnIor1unately thi.eppIieBtIon pI'OQIam cannot oulptlt data and measuresmultalleOUlly, Thill results in up 10 three IICOIlds ofmeasuremllllf 1I!'I'l8 being lost when~ Ihe data 10the computer al lhe.-nll or each measurement perlOlllso I"th is hu not been a problem). After Itlll progfll m was wrinenanother Apphcations Module (the Shon Term ApphcatlOOaModule BZ 7106) WBI released which should lWercome thisproblem and allow aimullanool' S measuremllnt and dalaO\Jtpl.ll with minimum meuuremenl perloll s aa short as one

"""'"A separale program haabeen wrille n 10 atOre8lther Pflak,

~~~~;:'~'~~'='~~king the lIOfIwlIre i1Yailableahould there be pal1<es inlerested

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AA IlKample oflfWt pn nled OUlPIJI

NO NONSENSENOISE CONTROLSPECIFICATIONSAC Powe r Input22G-250V 50/60 Hz, 7VA. (Other voltages to order .)

Trigg er Range60 dB-129dB . (40 dB·l09 dB with opllo na l high ga inrmcrcp bcne.)InputWeighlfn gLinear. A law ,exlernal.Trigger Level:t 0.25 dB.Response± O.5 dB 30 Hz· 15 Khz.Timing AeeuracyNominal ± 0.05%. Sub jecllo mains supp ly accurac y.AC Monitor OutputOdSm allrlgger level.Switched OutputIsolated micr osw itch relay. Max. load 240V 2A. AC.

WITH A GASCOM 2376NOISE MONITOR

• Success luli rutflisedbyloclllgo~ernmen r, Induslry, commercialsites and in 9ntertainme nt Ifenues.

• Easily insra lled by any licensedelectr lcalconrracIOf . Full installa­tlon manu al supplied.

• Simpl y dial up requ;red Ihresho ldlevel when insralJed.

• Tamper pr oof -locking steelenclosure prelfents un8ulhorlsadadjusfment.

• Calibration is achie ved usin g aBruel & Ki aer sound level calibra tortype 4230 wi th 12.5 mm ( 1,7 inch)adaptor ,

GREAT AUSTRALIAN SOUND COMPA NY(02) 4064588. FAX (02) 4066660

Box 570, WiIloughby,N.S .W. 2068,Au strall a41108 Warr ane Road, Chatswood 2067

Power Statio n Noise Reduct ionNew' Release from NAP SILENTFLO(1) Katharine , Northern Teft llOl'Y

Katherine, located in the 'ar nort h o f the NorthernTerritory, a major tOliriSt destinat ion, agricul tural andbeel produ cmg areas and home to the majo r TindallAAAF base, is also the recipient 01 a state 01 the artneturar gas-Ilre d power stall on. In 1981, Solar TurbinasAustraliaPty Ud won a contract to build and hand overa complete turnk ey unmanned bese load powe r slation ,and noisa abatement was one of the critical la ctorsidentified early in the plannino phase.

Realising the problem thet tndustrtet noise pollut ionpose~ tor power station sreu ene local residents, SolarTllr bmes call ed tenders and finally seleCle d well -knownacoust ic des igner and manufacture r. Nap SilenlRo.Nap's Managin g Director, MI Tim Marks, said the taskwas to eohteve a guaranteed 85dB {A) noise suppross­Ion al 1 metre, near fie ld Irom ailiurbine powe r relatedequipment and NR ~5 at 100 m in any direc tion 'r omtha station. Acco rdIngly , the compan y designed, pre­fabr icated and supplied three ci rcularlurbine exhausteaencere, turb ine inlet airdllc twOl k and eueecere. andmachine hall eccusnc enclosures, Venti lation duct ­~~~t~~~~~ s and silencers wore supplied und er separate

The results shOWed that, whilst Internal noise levelsrise to over 100 dB(A), measurements al 5 m Irom anypOint 01 the eocic svre have not shown ambianl noisegreater lhan 65dB(A).

(2) Hau lwood. Victori aHazelwood Power Statio n near Morwell In Victo ria

is a coal-fir ed station capable of producing up to 1600megawatt. Bum in the early sb t les it is cUl rently mid·

way through a Plant life ExtensIon plogramme whichwili lenll then its uselul worki ng life by 15·20 years, Inan effort tl? enhanc e the working ,environment lor thepower statIon's operators and mamtenance crews theSEC In 1986 issue<l a speci fication to reduce the noi selevels ranging up to 105 dB(A). al the fao 's inlat, whichis where maximum noise is generated. Each F.D-. tanprovides 161 m"! s 01 combustion air for the putvensedcoal , which is used to fire _the plant's boilers.

The major requi rement any tenderer had to achievewith this project was a eoree level of 85 dB(A) at 1 mat maximum desig n rati ng, whilst still allow ing operatingand maintenance s1aff 10 have full access 10 tans, motorbearings, couplings and intet vane actuator s severaltimes a day. A lurther requirement 01 the scccmc ancnwas that Ihe equip mell l had to be able to wi thstandthe butfe ting enecrs of wind loading.

Nap's Chli s Beale, the project engineer on theHu elwood proj ect says, " the noise contro l system hasto cope with int~,"al negative pressure generated bythe F,D. fan plaCing severe buflet lng ont o the plenumstructure, causing conti nuous stress.vln essence, NapSllentlto 's approach was multi-faceted.(1) Acoustic cl adding was appl ied to Ian casa and dis­

crerce ucct.(2) l oaded viny l cladding was attached to the 870 kw

CACW electri c motor-driver .(3) A plenum, consi sting 01 Nap's demountable Sound

Snap acoustic panels was designed 10 suppressnoise compar ablewilh that of the inle t sile ncer.

(4) Indlls tr ial versions of Nap'lI " 0" ser ies sl lence~

were insIa lled 10 each 01 me.ran air Inlels .Str ict testing by the clle nl's engineers has proven

the noise rec ucnc n required hIlS indeed been achievedwhi lst access was maintained.

The Acoustic Properties of Wood in Relation toStringed Musical Instruments *J.I . DunlopSchoo l of PhysicsUnIvers Ity of New South Wales

ABSTRACT: VotlodIlIlS been and remains the mosl flNOUredcilQ/ce01material vsoorofabricate tilebodies 01 stringed mtJsical Insrroments. TIle mecll8nical properties 01 wood are relaUJd to itsmorphoIogicai SlnJcl vre and maktlil vniqve espec lal/ylnslrengtll ·lo-waig llt rario , nd anisolropt InITIO$t woods Me acoustic I'8SocIfy. • moosureof its modulu1, l'lrie s from 3-6 kmls ,long til e f1IiIin 100.8 . 1.8 kmlll across /he grain. TIle vtxation da mpinQ Joss In woods is due to _ raJmoJeculartrItIdlanisms . nd~ Ofl t&mpetalure, ItequefICy and moistu re content , the /ogan'lhmicc1ec{Bmenl /;leingin the region 1~ _ 1(}-Z. The c/Ioi(:.eofwoodstradifiorlaNyuSfld iniflslnJments!/lowS some unique combinations at these ptopfIrlPes _ asfJf1CiaJJy In the ralios at lateral fOlong itUdinal rnod/Jlus. the rallo at longitudinal >'9Iocity to dfJnsity and tile Inlemaldompfng attftawoods

INTRODUCTIONViol in makE!f$ha'19always pa id parhcula r allllfllion to theirselect ion olwoocl not only 3S a spec ies but also lor thecoaraet!tl'ishcs 01a part icu lar p;eceus.ed. In Europe it l'Iasbeen lradltiooal to U$8 sottwood coni le rs -and us ually 10use dillerenl woods in differenl parts 01 lhe instl'l;ment Inpartlcu larN ofWayspruce(Piooa excelsa)h as beenfavouredfor top plates and NOfWay maple (Acer plalanoides)!Ofbacks, However a wide variely of woods has been usedsuccess lu lly and this coes nol exclude Australian timberswhich arll unique to this part of the workl . Fore xample, l herllis a collection 01 fine violins at the Sydney Musll um 01Applied SCienCll lo illustr atethesuccess 01bolh AustraliantimbMs and Australian viol in maker1;

SCie"lific measut9m8f1t of the mecha nical and acousticproperties 01woods is extensfve, and much o/ this work isdocumented. Properties of importance ere eiestc rnodulus(dynami C),denistyandaooushcdamplngandthis scianti ficdata mighloo utmsed by the violin makers.

STRUCTURE OF WOODThe unique mechanical properties of wood - its highstrengthloweighl andanlsotropic ralios _arisebecauMoIitS morpholog ical structure_ WOOd is a COfnp(ll;ltll materIalconsi sting of an assembly of long thin hollow cel ls. the .. eusoI .. hich are Iormed of cellulose micro/ibri ls embeddi ng in amatr ix o/llgnln. These cells, (traCheids). arllal lgned alonglhe wood grain and cemented together by a matri x of lignin.The fracheids comprise the majot componen l 01wood andacco unt lor its high slrengfh . There is, however, a wide range01the dlstrib utlon ottracnejd s'zes and other rnorphologicalcomponllf11S. part icularly i" hardwoods . these varialKlnsdi stingu lsh lngonespecies homanotner

The properties 01 ,he ,rache id and the embedd Ing lignincontrol the fesu~ing bulk wood properties , l ignin is anamorphoUS com plex mater,al 01 polys acch a'ides . phenolswlth a low (relatively}ela stic modulus 2,61: .3GPalCotJ sillS,Armstrong and Robinson 19751 as measu red by a"Il'ldenlation fechnique fts aCOusflc properties have notoo enseparately measured . The tracheid or wood cell oUers acomplex. structure as shown I" Flg.1. being composed 01cell ...lose microfibrils IImbecldlld in a lignin matrix. Thecel lulose occurs as extremely f/lin/1Q.20me cross secrKln)long llfId strff (Young's modulus 300G Pa) "bri ls In acrystalline lorm (Cave 1968).

These fibrils and microfibril s neve dtstmct coemencnpatterns in the cell wall as shown in Fig.1. The majorcomponent /80% ) is ltI lI S2 layer In which Ihe micro l ibri lsare aligned B1 a small angle 10 the cen Ofillntalion and

Fig.1 Simplil>ad. 'UClUl'Ilol thacell _ Mol a lrac_

.. hichcontr iOOllls lOf/lehignlongrtudlnalst rellflt holtheoollThe other layers $1 and S3 playa'" important role ins1abilisinglhes,ruc'u re aQainst lateraldelorntatlons

The elast ic modulus 01 wood Is fherefore anisolroplc ,being much sl ronger along Itlegrain men across it. Thelongitudinal modul us can ee adequately accou nted lor inlermso/the orienlatl onof lhemicrol ibrils. .. hichvarieslromspecies to species and also within thes ame tree. In Fig.2areshown measurements ~aling the Iongtitu dlnal elasticmodufuso/ a wooclsample to ils positiooi" Ihetree~ativeto

10 20

RING ORDER

Fig.2 RelationbetweenYoung'sModulusand ring order (CowdreyandPreston,1966).

ring number. The higher elastic modulus values in the lategrowth regions (at the outside of the trunk) are due to thesmalierorientation angle of the microtibrtls,

The lateral modulus is much smaller due to the largerorientation angle of the 82 microfibrils and to the muchgreater proportion of lignin, between and within tracheids,acting in a load bearing capacity. The lateral modulus is alsodependent on the orientation of the sample-whether it isradial (quarter cut) or tangential (slab cut)-it being amaximum for radial, reaching a minimum at 450 orientation(skew cut) and increasing again towards 90° (slab cut).

There is much variability inthe structure of wood betweenspecies, particularly in the uniformity of tracheid sizes. Thisis especialiy so in hardwoods which exhibit a wide range ofceli diameters and are further complicated by the distributionof non-structural celis responsible for tree metabolism, suchas vessels, many aligned in the lateral or cross graindirection. This can therefore lead to wide variations inwood'smechanical properties.

A further important eHect on the mechanical propertieswhich must be considered isthe uptake of water or moistureby wood. This can range from 0% for oven dried wood to30% (on dry weight) before surplus water is evident. Themoisture content aHects the mechanical properties-woodbeing "stiffer" or of higher elastic modulus when dry. Themoisture is capable of disrupting molecular bonds in thematrix thus reducing stiffness. It cannot enter the crystaliineceliulosemicrofibrils.

ACOUSTIC VELOCITY

TABLE 1Mechanicalpropertiesof wood(fromHaines1979)

Wood spruces cedar maples rosewood

Denslty(p) 470 390 650 730(kg/ms)

Acousticvelocity(kmls):

5.5 4.8 4.0 4.1Long~udinal C,LateraiCt 1.4 1.4 1.8 1.8

Young'smodulus(GPa):

Long~udinal E, 14.2 9.0 10.4 12.3l.ateralE, 0.9 0.75 2.1 2.4

Log.decremant:.023 .015 .038 .023Longitudinal

Lateral .067 .038 .067 .042

Ratios:

EtE, .06 .08 .20 .21Clip 11.7 12.3 6.2 5.6

ACOUSTIC DAMPINGThe vibration damping properties of woods are of relevanceto their use in musical instruments. This damping resultsinaloss of acoustic energy and hence can reduce theeffectiveness of an instrument producing sounds. Dampingor damping loss may be characterised by the decay time-the time required for vibrations to decay-or bytheQofthe material, which may be determined from the bandwidthof a wood sample's resonance curve, thegreatertheQthelower the damping. Both measures have been used in thepast to specify vibration damping.

Inwood there are several diHerent mechanisms that maycause damping of acoustic vibrations. The particularmechanism involved wili depend primarily on the frequencyof vibration. At very high frequencies, smali motions of atomswili generate heat and cause damping. At very lowfrequencies (e.g. creep or viscous flow) largescale motion ofmolecular sections have a similar eHect. Each mechanismhas a characteristic time constant and damping will be atmaximum when the frequency of vibration matches theresonant or characteristic frequency of the particulardamping mechanism the reciprocal of the decay time).

Fig.3 Dampingloss versus temperaturefor variousmoislure con­tents(Dunlop,1978).

The mechanical properties of relevance to instrumentmaking appear to be Young's modulus in the longitudinal (ingrain) and in the lateral (cross grain) directions and therespective loss moduli or damping constants. Shear modulimay have some effect but this is considered to be minor.Acoustic velocity or sound speed of a medium has beenwidely used to characterise woods. It is related to themechanical properties by the equation

C ~ (E/p)'h (1)whereE is Young's modulus, and Pisdensity.

A .wide range of acoustic velocity values have beenmeasured for different woods. In the longitudinal direction,i.e. along the grain, sound speed may vary from 3t06 km/s.Across the grain it is much lower ranging from 0.8 to 1.8km/s.The most useful modern data is that due to Haines [1979)whomade measurements on a wide range of woods of interest toluthiers. Some of his data are summarised in Table 1, fromwhich can be noted the marked anisotrophy attributed towood's unique morphological structure.

r ,~20.•7.

1(;4

- :.7.

H:C

0.7. ...

These damping mechanisms are located in the lignin asthe cellulosic microfibrils are highly crystalline, relativelyimpermeable to water and have extremely low damping.Thus damping measured inthe longitudinal direction (alongthe grain) is much lower than on the lateral direction, [Dunlop1978]- by a factor of 3 for softwoods, slightly less forhardwoods. The values of damping observed by Haines atdifferent frequencies in the audio range are indicated inTable1forsomewoodsofinteresttoluthiers.

Another important factor which affects damping is thetemperature of the material. At lev temperatures the materialappears to freeze and hence the characteristic frequency ofthe damping mechanisms is increased. If the damping ismeasured at different temperatures the results shown inFig.3 are typical. These show the damping in wood at 45 kHzas a function of temperature for various moisture contents.Similar curves at a frequency of 1 Hz have been obtained byNoack and Becker [196B).

The frequency range of interest to musical instruments is100 Hz to 20000 Hz at room temperatures. This region isindicated on the graph of Fig.4. and it can be seen that it fallsbetween the maxima of the two damping mechanismsindicated. The damping from each mechanism overlaps theregion but the damping from the high temperaturemechanism especially at high moisture contents probablypredominates. Damping of wood instruments would berelatively greater in hot humid' conditions and be moreevident at low frequencies. Conversely some slight increasein high frequency damping may occur at low temperatures.

Each damping mechanism is therefore characterised bycombinations of frequency and temperature at which thedamping is maximum. This phenomenon can be illustratedgraphically as shown in Fig.4. On this graph two straight linesare shown determining the positions (in frequency andtemperature) where the damping of two separatemechanisms are located. The higher temperaturemechanism [Noack and Becker] is considered to be due tolargescale motion of side chains in the lignin molecules. Thelower temperature mechanism [Dunlop 1978J is due toabsorbed water in the wood structure, principally the lignin.

1 2 3 4 5

1000/(TEMPERATURE OK)

STRUCTURE OF INSTRUMENTSThe most usual structure of string instruments is a closedbox with relatively short stiff sides. The top and bottom platesare excited into flexural vibrations, which are the principalsource of sound. The sounds emitted by the instrument willdepend on the vibration patternsexcited,which in turn will bedirectly dependent on the properties of the wood.

The top plate with itsf holes and crossbar has beentradi­tionallydesigned as the principal sound source and thechoice of woods used in its construction has been mostrestricted. Recent analyses of the top plate vibrations usingfinite element analysis [Schumacher 19BB]have indicatedthat the critical properties of the wood used are Young'smod­ulus in the longitudinal and lateral directions and the shearmodulus perpendicular to the longitudinal direction. Theseproperties of the wood determine the mode shapes possiblewithin the dimensional constraints of the plate and hencedetermine the tonal character of the instrument. In the mostcommon choice of woods the ratio of lateral to longitudinalmodulus (EtIEI) is fairly closely maintained at 0.06 in spruce(for violins) and slightly greater at O.OB in cedars (for guitars)usually from quarter cut section. For bottom plates, highervalues (up to 0.25) have been favoured in maples and rose­woods suggesting their greater role as a structural elementinthe instrument. There is some uncertainty in the necessityof reproducing these ratios however, as experiments byHaines [19BO]has shown that they can be substantially modi­tied (increased) by varnish and fillers, and plywoods havebeen used successfully in instruments.

The damping properties of the wood will also be influentialin characterising the tone of an instrument-the greater thedamping the "duller" willbethesound. Plate vibration damp­ingwilldependonthedampingpropertiesofitsconstituents-the wood, varnish and filler.The damping propertiesofvar­nishesareusuallymuchhigherthanthoseofwoodsbuttheexact contribution of each to instrument damping isuncer­tain.Traditionalchoiceofwoodsbyluthierssuggeststhatthedamping characteristic of the wood is most critical, andHaines notes that the very low damping constants of gUitarwoods (cedar and rosewood) are necessary for "sustain"and can be troublesome in violins.

The frequencies of modes excited in instrument plates willdependonseveralpropertiesofthewood-moduil,thick­ness and density. If traditional good instruments are to becopied there is a need to know when two pieces of wood areacoustically equivalent or matched -their elastic moduliand density may be different. As the main acoustic response

, ~~~~~ :~~~~;::~~~f~:~~X~~~1 ~~b:~~~~~~~~~::;:a~~~~'p~~~cn~-~ The flexural stiffness of a plate IS proportional to Eh', where~x ElsYoung'smodulusandhlsplatethlckness Thus for

~~~

matching Eoho' = E,h,'wherethesubscnptsOand1 refertoMUSICAL the old and new Instrument Equal densities per unit areaINS::~~EENT require that

DUNLOP (1978) Combining these two eq~~~I~;s ~~~' usrnq equation (1)yieldsCoIP, = C,lp,

ThlsmeansthatlfCandpcannotbedupilcatedseparatelythe ratio of C/p should be the same for both species and the

NOACK and BECKER 119681 thickness adjusted to obtain the correct mass per umt area.This assumes that the ratio of longitudinal to transversevelocity remains the same in both species (which may notalways be the case).Thischaracteristicofwood,the ratio ot Czp,has been usedpreviously to classify woods [Barducci and Pasqualini 194B]and Fig.5shows their representation of a wide selection oftimbers. In this diagram the valuesoftheQofeach timber (in-

FigA (~gm~:~~~~~s~~q~~~~;e~~e~i~;:~~t~~~o~~t~~i~~~i~:e~:~f~ ~:~~fg~~~~~~~n~~ ~e~~Ot~~t~sn:~~~~~i~nea~~1~i~f;jtd,F~~~way spruce, (Picea excelsa) exhibits both a high C/p ratio

100,000

~ 10,000

u1,000z

lJ.J:J

~100

10

and low damping. Norway maple (Acer platanoides) a tradi­tional back plate wood has a much lower C/P ratio andhigher damping. Also of interest on this figureisThuja plicata(a cedar) that exhibits more pronounced features in terms ofC/P ratio and damping than Norway spruce and is oftenused for guitars.

CONCLUSIONThere is still much uncertainty in the connection between themechanical properties of woods and their performance instringed rnucical instruments. The characteristics of good tra­ditional instruments suggest some of the properties whichappear to be critical and hence should be sought-a highC/pratio in the grain direction, low damping and low ElE,modulus ratio-for the top plate in particular. Thus somewood characteristics might be favoured such as wood spe­cies, with late wood growths and quarter cuts being prefer­red. The properties of woods found in other components ofthe instrument appear to be less unique in theircharactens­tics.

There are, however, many other factors which can effectthe ultimate performance of the instrument-the. effects ofvarnishes and fillers used to finish the instrument and the var­iabilities inherent to hand made products. Thus it is certainthat the skills and intuition of the maker will continue to playamajor role in determining the quality of the finishedinstrument.

REFERENCESBarducci I. and PasqualiniG. (1948)Nuovo cimento 5,416-446CaveI.D.(1968)Wood Science and Technology 2, 268-78;3,40-48.Cousins WJ., Armstrong RW. and Robinson WH. (1975)J Mat.Science 10,1655-1658CowdreyD.R.andPrestonR.D.(1966)Proc.Roy Soc. B168,245-72DunlopJ.I.(1978)WoodScience and Techn%gy 12,49-62HainesDW.(1979jCatgutAcousticaISocietyNewsletter,#31,23-32.HainesDW. (1980)Ibid#3319-23.~~~ckD.andBeckerH.(1968)WoOdSCienceandTeChnOIOgY2,213-

SchumacherR.T.(1988)J.Acoust. Soc. Am., 84, 1223-1235.

(Received 8 Dec. 1988)

"Based on Leclureto 1988 Annual Convention and Exhibition ofInstruments held by Australian Association of Musical InstrumentMakers,Epping,N.S.WOctober22-24,1988

A Violin Quality Assessment Method: Study IIGraham Caldersmith20 DryandaStreetO'Connor ACT 2601

ABSTRACT: The second phase of a study for assessing violin quality is discussed. The test soundscomprised an open note and an octave scale on each string of three different violins played by thesame performer. An audience of 29 listeners from the 1989Chamber Music Summer School at MountBuller, Victoria made assessments of Projection (Carrying Power) and Tone Quality for each of theviolins played.

INTRODUCTIONA pilot study in a violin quality assessment method wasreported in Acoustics Australia [1] following theadministrationofaviolinqualityratingexerciseatthet988Riverina Summer School for Strings (Wagga, NSW). Thisrating exercise was performed by scoring four unseenviolins,A, B,C, Dforseven quality properties on a scale of+2 to -2 during cycles of playing by two violinists. It wasanticipated that this rating procedure would be refined insubsequent administrations in the light of the pilot study andin response to feedback from the audiences and violinistsperforming the rating procedure. This paper reports on asecond rating exercise at the January 1989 Chamber MusicSummer School hosted by the Australian String Quartet atMount Buller, Victoria.

METHODThe 1989 Mt. Buller Summer School, accommodated in thecomfortable Jungfrau and Benallalodges,drewaboutfortyparticipants ranging in age from 17tosenioryears, dedicatedamateurs and full time string students. On this occasion theparticipants were introduced to the rating method at theinaugural evening "Happy Hour" by rating two red winesbetween +2 and -2 for six qualities on a "wine rating form".Aftersomeintensivetipplingbyyoungandold,theindividualratings were totalled to give a rough measure of the groupconsensus on the wine qualities. Though the results weremeaningless due to an apparently random spread of groupopinion,indicatingalackofconsensus(beyondthepersonalpreferences recorded), familiarisation with the method inpreparation for the violin rating was accomplished amidstbravado and vigorous debate.

The instructions heading the Violin Rating Forms were: "Ifthe violin you are hearing (or playing) impresses you with anyof the properties set out below, write a +1, and if theimpression is strong, write a +2. If the violin strikes you asdeficient in any of the properties, write a -10r -2 accordingtothedegreeofdeficiency.WriteaDifyoufeeltheviolinisaverage or normal for that property. Only write next to thoseproperties you consider meaningful. Comments are helpful."

The +2to -2 scale is regarded as more meaningful than1-5 or HD because the participants can quantify eachproperty within two degrees of positive or negative above orbelow the normal or averageD, which stands as a qualityreference point. Thus terms typically used to describesensory impressions which are usually subjective can bequantified: excellent ~ +2, good ~ +1, average ~ D,poor ~ -1 and very poor ~ -2 (and more vernacularequivalent terms can be colourfully employed within thesame scale).

Participants at the 1988Wagga Summer School had foundsome difficulty in rating seven properties between +2 and-2 for each of the four violins, so for the 1989 Mt. BullerSchool the properties were reduced to five as shown in Table1. However when the exercise was performed on the evening

TABLE 1Violin Rating Form I

Property Violin A ViolinB VlolinC VlolinD

Projection orCarrying Power

Tr~~~~~~~\~I~d)~~

~~~ity r~~~~~~~=rSh)r~~~edorBOXY)

Total

For Players: Evenness,Ease of Response

of Jan. 24,confusion about the meaning of the propertieswas expressed, first whether the words chosen to denoteaudible qualities could be regarded as -i-, - poles of thosequalities, and second, if the propertieswereindependenl:e.g. "brightness and clarity" could well be components of"projection and carrying power". Members of the AustralianString Quartet suggested a further simplification of the ratingform and playing format. This discussion resulted in the"bare essentials" form shown in Table 2 with which a second

TABLE 2Violin Raling Form II ("Bare Essentials")

Property Violin A ViolinB ViolinC Violin 0

Projection orCarrying Power

Tone Quality

Total

For Players: Evenness,Ease of Response

exercise in rating three violins with one player was performedon Friday Jan. 27.The playing format was also simplified toan open note then an octave scale on each string of eachviolin, whereas on the Tuesday session two players hadplayedatwo-octavescaleandanexcerptofaBachpartitaoneach violin.

On each occasion the audience listened to a playing cycleonallviolinstofamiliarisewiththetaskbeforerecordingtheirscores during two more playing cycles. As at the WaggaSchool,the audience faced away from the player(sjsotheycould not see the instruments which were only identified asA, B, C, D as they were played. This arrangement alsoreduces the level of direct sound heard by the listeners, sothat the ratings depend more on indirect or reverberantsound, which is a fairer representation of a violin's overallperformance.

As in the introductory wine rating exercise, the individualscores were totalled for each property, publicly, from a showof hands and recorded on an enlarged rating form displayedon a wall. This exhibited immediately some measure of thegroup opinion on the qualities of the three violins and in theshowing of hands the level of agreement amongst theaudienceontheratedpropertieswasindicated,aprocedureinciting lively debate about the relative merits of the threeviolins.

AUDIENCE RESPONSE TO THERATING PROCEDURE

The condensed rating form enabled all 29 listeners tocomplete ratings of two properties per violin within the twoplaying cycles (following the familiarisation cycle) of opennotesand octave scales on each string of the three violins. (Inthe Tuesday rating, five properties for four violins had to beassessed). Most listeners thought the condensed formallowed better focus on each instrument, though eliminationof subdivisions in "tone quality" increased uncertainty aboutthe nature of that property i.e. some found resolving thisimportant but ill-defined property into components specifiedits nature and assisted rating. There seems to be a trade-offbetween the simplicity of the rating form andthe definition ofthe properties rated.

Several listeners entered comments in the space providedon the forms and registered impressions about the charac­teristics of the violins on the different strings, a commontheme in discussions of violin quality. The open string andoctave playing format encourages this perception. Somelisteners fell a piece of music played (as in the Tuesdaysession) is necessary for an impression of musical quality In

rating an instrument.

Naturally great interest in the relative scores of the threeviolins was inspired during the public summation of theratings, and the final identification of the instruments, A, Band Cstimulated comment, debate and requests to try theinstruments in private to asce~ain whether the audiblecharacteristics corresponded With playing characteristics.The value of focusing attention on the tonal properties ofdifferent violins in this rating exercise was generallyacknowledged.

Property

ToneQuality

~:~::~ ~~ ~~~O~;~~~li~~~~~~~~~~~~~ ~~~~% ~~I~~~~~~~rneridelGesu,1733.

ViolinC: "good" violin,J.B.Guadagnini,1751

DISCUSSIONTable 3 shows average ratings on the +2 to -2 scale andthe standard deviations derived from the 29 "bare essen­tials" rating forms completed on Friday 27 Jan. Results fromIheTuesday 24 Jan. rating are not shown due to the confu­sion expressed by the audience about the meaning ofthe properties and their opposites. In brackets are shown theaverage ratings and standard deviations for 13violimsts In

the audience of 29 musicians.

While the standard deviations (s.d.s) were with oneexception less than 1,the unit of the rating scale, indicatingan acceptable consensus of audience opinion on theproperties of the violins, the average s.d.'s in the totals wereabout the same as those derived from the 1988Waggaratingexercise. Hence no improvement in consensus wasachieved by familiarising the Ml. Buller audience with therating method and by condensing the rating form to allowbetter focus on the fewer properties to be rated. This isdisappointing, but perhaps not unexpected after the debateabout the subjective meaning of the properties being rated,the appropriate playing format and the listening conditions.Given that the individuals in the audience are assigning ameasure of quality to an enormously complex auditory signalfrom a variety of backgrounds and musical experiences, thepossibility that we may never achieve greater consensus(evident in smallers.d.'sjthan reported in these studies mustbe considered. This would imply that the variation of opinionon violin tone measured in these string-playing audiences isa fair indication of the range of taste in the musicalcommunity at this time and place in history.

Nevertheless there are some trends in the s.d.'swhich areworth noting. While it was found in the Wagga study that thelowest s.d. in scores occurred with the highest ratings, inthisstudy, the violin C rated highest by the 13 violinists had thelowest s.d.'s. but the next highest rated violin B (in factstatistically equivalent to the highest rated) had the largests.d.'s.We cannot attach high significance to the resullsfromsuch a low sample under (13), except to observe that bothviolinists and total audience varied much more in theiropinions of violin B's quality than they did for violin C.Comments on the rating forms referred to B's "full", "rich","mellow" and "open" lower range sound while C wasconsidered "balanced" and "even". Further discussion withparticipants suggested it is harder to interpret a strongimpression in the lower strings than a "balanced" one, andthis may account for the different consensus of opinion ontwo violins of overall equal quality rating.

The three violins used in this rating were chosen aftercriticism from the Tuesday rating that the four violinspresentedonthatoccasionwereallgoodinstrumentsanddifficult to distinguish. Hence for the Friday rating I selected ademonstrably "good" violin, a demonstrably "poor" violin {inthe opinion of its owner) and an untried new violin. The"good" violin was a prime example of the work of JohannesBaptista Guadagnini (1711-1786) who, with Carlo Bergonzi, isregarded as the principal heir to the standards and traditionsbequeathed by Stradivari. This instrument of 175t wasacquired in 1952 from connoisseur and dealer EmileFrancais by teacher and benefactor Richard Goldner (whoinitiatedMusicaVivainAustralia)andsubsequentlydonatedtoapromisingsoloist.ltisnowheldintrustforassignmenttoleading Australian musicians, currently William Hennessey,leader of the Australian String Quartet, who made it availablefor this exercise.

The "poor" violin was a mid nineteenth centuryMittenwaldinstrument,nicelycraftedinattractivetonewoodswithhighbellyandbackarching.ltsevidentmediocrity{asrated) may be due to its state of adjustment rather than itsacoustic design, although highly arched violins are rarelyfavoured for modern playing styles. The new violin was madein Australia in 19BBto a pattern of Guarneri del Gesu, 1733.

A critic of this method for assigning a measure of quality toa violin from audience ratings might raise objections citingthe complexity of the tone production, transmission,reverberation, reception and assessment processes uponwhich a quality judgement depends. The variable effects ofthe player{s) on the different instruments, the type ofexercises and examples played, the state of adjustment ofthe instruments, etc. may also be debated. It is pertinent toreply that all these objections apply to every other situation inwhich violins are judged in subjective terms and where non­musical factors bear heavily on the qualities assigned. Thismethod removes two of the strongest non-musical factorsfrom the assessment process: the age of the violin and itsmaker and the expressed opinion of the most experienced orassertive musician involved. In this case all the violins werestrung with PirastroEudoxa, the same notes were played bythe same violinist with the same bow in a reasonably rever­berantroom. In theWaggaexercise and the first Mt. Bullerexercise two violinists played and differences in qualities dueto differences in styles were noted. One violinist argued thatthe differences due to playing styles were greater than thedifferences between violins, but most listeners were satisfiedthat the audible qualities of the violins played emergedthrough the playing styles.

The result that a raw(little-played) modern violin was ratedessentially equal to an Old Italian Master Instrument issurprising to string players subject to the premise that oldpedigree instruments are unsurpassed in projection andtone quality. In fact objective comparisons of old and newprofessionally crafted instruments conducted since the1930's [e.g. 2, 3,4] demonstrates the inability of connois­seurs and audiences to distinguish between old and newinstruments. Playing tests are harder to devise since playersreceive many non-musical cues from the instruments theyhold, even blindfolded. The evenness and ease of responseof a superior instrument inspires security and confidence inthe player, and is regarded as the ultimate test of aninstrument's quality even when listeners cannot distinguishdifferences. Old violins are held to excel in ease of response,and apocryphal accounts of the majestic powers theyrelease in players adorn the pages of violin journals, suchaccounts being now de rigeurforjournalistic respectability.Hearts duly inflamed to gain admittance to the league of theOld Italian Sound, string musicians are driven to financialhaemorrhage to meet the prices commanded by theassumed musical masterpieces, thereby feeding the cycle ofsupply and demand for rare violins. Within this establishedscenario the committed musicians cannot afford to evencontemplate the equivalence of old and new violins and soobjective comparisons are not approved or recognised. Oneof the unfortunate consequences is that musicians payexcessive prices for even mediocre old instruments and donot consider seeking superior new ones. Fortunately severalleading virtuosos perform and record routinely on newinstruments at no disadvantage to quality of sound.

CONCWSIONWe have reported hereon a second Violin Quality RatingExercise following a foregoing (19BB)pilot study of the ratingprocedure. Redesign of the rating form and administrationformat in an attempt to improve audience consensus on therated qualities will continue, even though no consensusimprovement in the rating was achieved in this second study.

ACKNOWLEDGEMENTSI am sincerely grateful to Jim Vizard for inviting me tocontribute to the 1989 Mt. Buller Summer School and forfostering this assessment exercise amongst the participants.Eleanor Lea and Tamsin Bailleyconscientiously played allviolins as fairly as possible for the ratings.

This is another study in a program of music acousticresearch funded by the Australian Research Council.

REFERENCES1. Caldersmith, G.w., "A Violin Quality Assessment Method:

Pilot Study", Acoustics Australia, 16,#3, 19BB.2. Saunders, FA, "The Mechanical Action of Instruments of

the Violin Family", J. Acoust. Soc.Am., 17,#3, 1946.3. Saunders, FA, "Studies of the Instruments of the Curtis

StringQuartet","Overtones",ApriI1940.4. Woodstock, C., Editor, Dictionary of Contemporary Violin

and Bow Makers (Introduction), Amati Publishing Ltd.,Brighton, Sussex, England, t965.

(Received 17 May 1989)

TECHNICAL NOTE

ACTIVE NOISE CONTROL iNSIDE AIRCRAFT

(From Laboratory News. July 1989)

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"Vibration creates the aircraft noise, so vibration actuatorshave to be positioned on the fuselage.

"That is a complicated exercise because it depends onthe size and areas which vibrate as to where the actuatorsmust be placed," said Dr. Hansen.

It is the second school of thought which the researchteam supports. Funding for the project runs out at the end ofthis year and the research team is not committed to havingsomething operational by then, but it must show that such asystem can work in a complicated cylinder similar to an air­craitfuselage.

k is thought that at the end of the year the Adelaide re­search team will have developed a teehnique for specific ap­plication to small aircraft with the eventual goal of producingthe hardware which can be retrofitted to existing light air­craft.

The project has great scope because the techniques de­velopedwill also be applicable to the control of noise insidemotor vehicles and ships, externally radiated noise fromships, noise from rotating machinery, engineexhausts,elec­~~~~. transformers and timber milling and metal cutting

"I guess the end result would be that aircraftmanufactur­ers would incorporate this system in new aircraft designs,"said Dr. Hansen.

ccmROL ~:r!LtNIC~~

VIBRATIO~ M~~'JSl!!}£...Tf rr.....A~TTV A' ~(.l:I8.~l~:1 t

BARRY CONTROLS a unit of Barry Wright

An active noise control system Is being devel­opedbythe universityof Adelaide's Department ofMechanical Engineering to reducenoiseInsideair­craft.

The project is particularly aimed at light aircraft and smallaircraft and is backed by a substantial governmenland pri­vatefundgrants.

Justoneyearold,theprojectgotoffthegroundwiththeinitial injection of a $182,500 grant from the Sir Ross and SirKeith Smith Fund. This grant was the first to be made by theFund since it's establishment in1986.

The Fund was set up in memory of South Australia's pio­neer aviators through the advancement of the science ofaeronautics in South Australia Lady Smith, Sir Keith Smith'swidow,bequeathedherentireestateforthispurpose.

This grant was followed by another of $60,000 through auniversity Research Grant and a Department of State Devel­opment and Technology Grant of $10,000.

Noise in an aircraft is an occupational hazard for pilots ofsmall aircraft and also affects passenger comfort. Most pilotshave ear damage afterafewyearsflying.

The six academic stalf members working on this projectare making good progress. The project is expected to re­ducenoiselevelsbyhalftothreequarters.

NASA is also working on a similar system in the UnitedStates, which can be adapted to larger aircraft.

One of the research team, Dr. Colin Hansen, said thegroup was constantly in touch with NASA and was workingin close co-operation with them.

"k's a situation where we are both lunded by our owncountries and are working together to achieve the sameend."

An effective noise control system is the activesuppres­sion 01 unwanted noise by the introduction of appropriatelyphased noise from one or more secondary sound sources.

"Noise energy cannot be cancelled on a global basis, al­though local areas of cancellation are possible. All the ex­perimentswe have conducted solar have involved manualcontrol, using frequency to find out whether a secondarynoise source should absorb some of the noise or changewhat the primary noise source radiated due to that seeon­darysound", he said.

"Construction of an automatic control system will adjustthe vibration actuator outputs to minimize interior noiseatanumber of locations and will adapt itself to changing aircraitoperating conditions.

"The key to noise control isto minimise the primary noisegetting past the secondary source.

"While noise energy cannot be cancelled out, as sometheories in the past have suggested,itcanbeabsorbedorchanged by using a secondary noise source.

Dr. Hansen also said there are two schools of thought onnoise control. "The first says a lot of speakers should beused insidetheaircraft,toachieve noise reduction atvari­ous, localised locations throughout the aircraft.

"Although speakers can control the noise coming into theaircraft, the problem is that the speakers don' minimise thetotal amount of noise energy coming in -they only achievelocal areas of reduced noise.

"The second school of thought says stop the noise com­ing in to start with. To do this the fuselage design must bechanged to reflect the noise from the propellers, rather thantransmit it into the aircraft.

REPORT

ACT Noise ControlOrdinance SeminarJoseph LaiDepartment of Mechanical EngineeringAustralian Defence Force AcademyCampbell, ACT 2600

A seminar on the ACT noise control ordinance wasorganised by the Acoustics and Vibration Centre at theAustralian Defence Force Academy and was held inthe afternoon on 11 May 1989. The aim of this half-dayseminar was to provide a forum to discuss the ACTNoise Control Ordinance which was introduced inNovember 1988 with the intention to review the provi­sions after 12 months of its operation. Speakers wereinvited from various sectors, inclUding the EnvironmentProtection Section of the ACT Adminstration, Comcareand Acoustics consultants. The seminar was attendedby about 40 people from academic institutions, govern­ment and industry sector, and various clubs andunions.

The seminar was held in two sessions. The firstsession dealt with the Ordinance itself while thesecond session took the form of a panel discussionand examined the various aspects of the Ordinance.In the first session, a background to the introductionof the Ordinance was outlined by Hugh Crawely,Manager, Environment Protection Section, ACT Admin­istration. The drafting of the Ordinance started inmid-1983 and was based on established noise controlmeasures adopted in all other States, and the recom­mendations by the National Medical and HealthResearch Council and Australian Standards. A briefintroduction to some of the terms used in the Ordinancesuch as sound pressure level, A-weighting function anddaily noise dose was given by Joseph Lai from theAcoustics & Vibration Centre. George Kniaht, from theEnvironment Protection Section of the ACT, then gavea summary of the Ordinance, emphasising that thepurpose of the Ordinance is to promote co-operationfora better acoustic environment rather than to prose­cute offenders. The Ordinance covers most noisegenerating sources except motor vehicles, animals,trains and aircraft. The Ordinance provides for protec-

~~~ni~~ait~~ ~r~t~~r~~v~o;o~~~e~~iV~en;:~~~ r~~~r~lti ~~the hours for operation of certain items such as lawnmowers and by prohibiting the sale-of articles exceed­ingthe prescribed levelsorofunlabeliedarticles.TheOrdinance also provides for hearing conservation inthe workplace by requiring noise reduction when anoise exposure exceeds a daily noise dose of 0.33.Between November 1988 and March 1989 there were1,189 complaints received compared with about 220per year prior to the introduction of the Ordinance.The major sources of complaints have been related tonoise from air conditioners and swimming pool pumps.So far only six noise direction notices have beenissued, and they have been complied with.

In the second session there were four speakers whoeach expressed their view on a particular aspect of theOrdinance. Marion Burgess from the Acoustics & Vibra­tion Centre pointed out two disadvantages of usingmeasured background level for the definition of excess-

:~~e~oi~ith nt~~:I~u~h~o inac~ei~~~e~~eb~~k~~~i~~~Sn~~~the difficulty in obtaining accurate representative back­ground noise levels under certain circumstances. GregAsh from Comcare examined the Ordinance from thepoint of view of hearing conservation in the workplaceand predicted that If the daily noise dose limit of 0.33specified in the Ordinance is adhered to, then thecompensation payout for hearing impairment will begreatly reduced. Mark Eisner, a private acousticalconsultant, representing himself and Eric Taylor (alsoa private acoustical consultant),discussedthe role ofan acoustical consultant dealing with noise problemsand commended the introduction of the Ordinance inthe ACT. The legal aspects of the Ordinance werediscussed by Oi Oibley, a lawyer. She considered thequantification of excessive noise as the greatest attn­bute of the Ordinance. However, in its present form,the Ordinance does not provide relief for noises most

~~~?!~~;:~l~~;i~~ff~c;~~~g:i~~:;;;~j~rit~~~:i~;able grounds" are not specific. What constitutes a"reasonable excuse" is unclear and has to beclanfledby test cases.

Each of the presentations had allowed for a shortquestion time but the general discussion was heldfollowing the last talk. A wide range of issues we~e

raised, ranging from control of animal noise, trafficnoise, skateboard ramp noise to heanng conserva.tlonin the workplace, clubs, concerts and at school socials.Concern was expressed about low frequency noise,such as that generated by music bands and the needto take into account the tonal components in the speci-

I~fl~:eJ~~:~~~~~i\i~~J~~!~~~~~~~~~~~:~~jiEv~sa~~ii~~according to the noise source, etc. It was pointed outthat this could be implemented in the Noise ControlManual to be prepared for use with the Ordinance. Itwas also sugoestedthat instead of usinq the measured

~~c~~~~~,n~c~~i~;a;l~ t~~u~~s~~:~I~ ~~~~~f~~gs~:~~i~sdfor areas throuqh a zoning system as adopted by someother States. It was felt that traffic noise should bebrouoht under the control of the Ordinance and that

~;n~~dr~~ci~nc~~~~:~~e A~V~~t~~e~~i~90P;~~~~cinh~~~posed as to the obllqation of parents and the s.choolauthorttv to hearing conservation of teenaoe childrenatlendinqrockcnncAtisorschoolsoc;;llsasapoarentIVthev are not protected under the Ordinance in suchsituations.

On the whole, the general f~eling at the seminar wasthat the Ordinance is a step In th"! rioht direction andeven in its current form it has alleviated some noiseproblems experienced by people in the ACT.

Modal Analysis:Four New Application Notes

Bruel&Kjaerhasreleasedfourshortapplication notes concerned with modalanalysis.

The first at these, Mobility Measure-

~:~:~'n P~~v\~:s frel~~o~it~r~~ti~~e~1~~of the applications.

An Introduction to Modal Testing out­Pnes the theory of mndal tsstlno andillustrates the ease with which a Bruel& Kiaer modal analysis system can beapplied to real-life problems.

How to determine the modal par-

~~i;5:i!~;:~;e{~!~g~;i:E~I~~~~i~

2032 Dual-channel Signal Analyser ora Type 2034.

The fo"rth aoolication note, Four­ChRnryel Morlol Tesfing. oxotarns how asimole modification within the Tvoe203~ or the Tyoe 2034 permits simul-

~~iJ~~~:i~:1r~:~:;~~~i;~~~e;~~~greater accuracy.

Activities in Department ofMechanical Engineering

David Bies

Department 01 Mechanical EngineeringUniversity of Adelaide

Our book, Engineering Noise Control: Theory andPractice, D A Bies and C H Hansen, Unwin Hyman, UK,became available in January of this year in Australia.It represents a development effort of about eight yearswith some very concentrated work in the last two.

Colin Hansen and I have also collaborated in thepreparation of three papers. Two on the relationshipbetween noise induced hearing loss and noise ex­posure have been submitted to JASA and are underreview. In these papers we show that noise inducedhearing loss scales on the integral of pressure (notpressure squared) with time and we show how to addthe effects of noise induced loss and presbycusis. Tomake our case we have used data provided by ISOdraflstandard 1999 and annexes. We have shown thatearlier work of Burns and Robinson and Glorig alsosupports our conclusion. As we are attacking ideaswhich have become deeply entrenched over a periodof 37 years we expect objections and thus we havecarefully prepared our case in expectation of a fight!

The third collaborative paper by Colin and me isconcerned with attenuation of sound propagating instraight lined ducts with mean flow of uniform butarbitrary cross section and bulk reacting anisotropiclinings covered by a limp membrane. Locally reactiveand isotropic bulk reacting linings are included as limit­ing cases. A considerable effort has gone into appro­priate programming as one of the two equations result­ing from the analysis is transcendental. However, weare now readily able to generate useful design curves

Australian Noise Abatement Policies-Some findings on their effectiveness

Marion Burgess

Postscript to Article in

Acoustics AustraliaVol 17, No 1 (1989) P 15

Since the preparation of the diagrams in Appendix A,the involvement of the Commonwealth environmentalagency (currently called the Department of the Arts,Sport, the Environment, Tourism and Territories(DASETT)) with the noise related committees of theAEC and ATAC has changed. Following a review ofthe best allocation 01 the limited staff resources within

in terms of convenient dimensionless variables. Thispaper will be submitted to JSV. It is also the subjectof a poster paper for the ASA May '89 meeting inSyracuse, NY. I will attend the latter meeting andpresent the paper.

Colin Hansen has taken up the pursuit of active noisecontrol. He and his very capable PhD student ScottSnyder have written several fundamental papers on thesubject. Other papers on the same subject have beenwritten by Pan Jie, C H Hansen and D A Bies. Besidesconference proceedings they will appear in JSV andJASA.

Graham Furnell, an applied mathematics studentjointly supervised by Dr Peter Gill of Applied Mathsand me, has recently submitted a PhD thesis on.thegeneral subject of sound propagation in ducts ofarbitrary curvature and cross section. He and I haveco-authored two papers on his subject describing newprocedures which will appear in JSV. This work rep­resents an important advance on the subject with verywide application.

Pan's thesis on room acoustics shows that in generalMorse's assumption of locally reactive walls can onlybe justified (considered true) when the acoustic fieldis diffuse. When the field is not diffuse then in generalmodal coupling between the acoustic field and thewalls of any enclosure will determine the acoustic fieldtransient response (reverberation time) and Morse'sassumption is then useless. While these facts havebeen recognised with respect to sound field responsein vehicles of various kinds no one appears to havepreviously made the extension to the important casesof architectural acoustics. One paper has previouslybeen published by Pan Jie and D A Bies and four moreare presently under review for publication in JASA.This work has important implications.

Dr Pan has addressed an issue in his thesis raisedby Morse himself in his fundamental 1939 paper, "Theoriginal analysis of the room acoustics problem", whichseems to have been totally ignored and never ques­tioned in the intervening fifty years of research andpublication on the subject with one exception. Evidenceof modal coupling in our reverberation room is des­cribed in a Master's thesis by Tom Munro, one of myformer students, but we didn't publish anything.

DASETT the department has decided that it must sub­stantially reduce its involvement in the environmentalnoise area in order to meet other priorities. Accord­ingly DASETT will no longer provide the secretariatfor the Environmental Noise Control Committee (ENCC)or for the Advisory Committee on Vehicle Emissionsand Noise (ACVEN).

The role of the secretariat for these committeesincludes assistance for the Chairman, preparation ofthe documents for the meetings and ensuring thatactions are taken on decisions agreed to at the meet­ings. The secretary from the Commonwealth agencyhas provided continuity for the committees and hasbeen able to play a key role in assisting consuitationand co-ordination between the relevant bodies onenvironmental noise matters.

At this stage no decision has been made on themanner in which the secretariat services will be pro­vided for ENCC and ACVEN in the future.

BOOK REVIEWSMACHINERY NOISE ANDDIAGNOSTICSRichard LyonButterworths, 1987, ISBN0-409-90101-6, Australian Distri­butor: Butterworths Pty Ltd, PO Box345, North Ryde, NSW 2113, HardCover, Price A$89.

Machinery Noise and Diagnosticsis a most welcome addition to thelibrary of books on noiseandvibra­tion. It is essentially aimed at post­graduate students and at practisingengineers and technologists con­cerned with the design of machineshaving less noise and vibration andat those concerned with utilisingdiagnostic systems for monitoringthe operations of individual mach­ines or complete processes. Thebook is well written and well pre­sentedanditisderivedfromlecturecourses given by the author to post­graduate students and practisingengineers over the past few years.Also, all the practical examples dis­cussed in the book are derived fromthe authors own consulting exper­iences.

The main strength of the book isits original and unique approach tonoise and vibration control. Empha­sis is placed on designing out mach­inery noise and vibration wherepossible, rather than implementing'band aid' solutions. The diagnosticpotential of noise and vibrationsig­nals is also clearly illustrated withthe aid of various basic and ad­vaneed signal analysis techniquesand with the emphasis being con­tinually placed on signal energylevels and signal phase. The bookcontains eight chapters and someuseful appendices.

Chapter 1 introduces the readerto machinery noise and diagnostics.Relationships between noise anddiagnosticsareidentified,goalsofnoise reduction compared to thoseof diagnostics are reviewed, generalfeatures of noise reduction pro­grammes are outlined logetherwithcost assessments, and diagnosticprocedures are introduced. Thechapter also emphasises noise re­duction by design and approachesto diagnostic system design. Thechapter is a clear statement of thetheme of the book and the readeris put in the correct frame of mind.The author's original and uniqueapproach to machinery noise andvibration is very evident from areading of this introductory chapter.

Chapter 2 is a fairly basic chapteron sources of vibration in machin-

ery noise. The author includes re­ciprocating imbalance, impact,elec­trical-mechanical analogies, pistonslap, crank slider vibration, dis­placement sources in gears andcams, fluctuating magnetic forces,diesel engine combustion pressure,and turbulent flow. The variousvibration sources are concisely dis­cussed and the reader needs torefer elsewhere if specific detailsare required. The author providesa short but useful list of relevantbooks, journals and magazines inthe bibliography.

Chapter 3 is a fundamental chap­ter about structural response toexcitation. The concepts of wavemotions in structures, power flow,wavenumbers, modal densities andreciprocity are introduced. Specificexamples pertaining to force trans­mission in machine structures,structural response to imbalance,modal response of finite structuresand isolator performance on flex­ible structures are presented. Thematerial contained in this chapterforms the basis for the important(but often neglected) topicofstruc­turebornesound. The reader isalso referred to other specialisedtextsonthissubjectinthebiblio­graphy.

Chapter 4 is on vibration trans­mission in machine structures. Theconceptsofstatisticalenergyanaly­sis (the subject of a previous anda forthcoming book by the author)are reviewed here. The concept ofusing statistical energy analysis fororganising vibration data is dis­cussed. This is a useful tool forconsultants when attempting toidentify vibration sources.

Chapter 5 is a general chapteron sound radiated by machines. Thetopics of radiation ratios, recipro­city, bending waves, reverberantsound power, radiation above andbelow critical frequencies etc. arediscussed here, together with num­erical methods of sound radiation.The topics covered in this chapterwhilst not unique to this book arepresented in the authors own styleand relate to various sections inother parts of the book.

Chapters 6, 7, and 8 are to alarge extent the core of this book.Advanced readers could bypasschapters 2-Sand delve straight intothese chapters which deal withadvanced machinery noise diag­nostic topics. Much of the workpresented here relates to the auth­ors own research and consultinqexperiences.

Chapter 6 is about diagnostics

using signal energy. High frequencyresonance techniques for bearingdiagnostics are discussed logetherwith powercepstrum,transferfunc­tion and inverse filters. Examplesrelating toa horizontal centrifuge,valve seat impact, and valve reson­ance are discussed in some detail.

Chapter 7 is about diagnosticsusingsignalphase-i.e.,thephasecharacteristics of structural trans­fer functions. The procedure ofwaveform recovery is discussed insome detail with specific referencebeing made to cylinder pressure.The chapter includes discussionson the poles and zeros of transferfunctions, phase variability, andnon-minimum phase systems. Thechapter is unique as far as noiseandvibrationdiagnosticsgoes,andin essence it is about recoveringthe temporal waveform of a sourceof vibration and other aspects ofdiagnostics using the phaseofasignal. Whilst emphasis is placedon cylinder pressure recovery,enongh specific information aboutthe procedure is provided for thereader to consider using it for otherapplications-proceduresfortheconstruction of inverse filters basedon measured data are also providedin the appendices.

Chapter 8 delves into some ofthe more advanced diagnostictopics including waveform recoveryfor sources that operate simultan­eously,diagnoticsystem design andapplication, and system identifica­tion using orthonormal functions.Chapters 6 and 7 need to be readprior to attempting chapter 8.

The appendiecs contain someuseful topics inclUding FourierSeries, Fourier Transforms, Fre­quency Analysis, Z-Transforms,Inverse Z-Transforms, DiscreteFourier Transforms, Hilbert Trans­forms, Cepstra, criteria for machin­ery noise and vibration, and, asalready mentioned, procedures forthe construction of inverse filtersbased on measured data.

In summary, Machinery Noise andDiagnostics is a book that all noiseand vibration researchers, post­graduate students and consultingengineers should have on theirbookshelves. Although the specificpractical examples in the book arelimited to the author's own experi­ences, the fundamental principles,analysis techniques and proceduresdescribed are intentionally pre­sented in a very general format soas to be applicable to most engin­eering noise and vibration prob­lems. Techniques such as recip-

BookReviewsrocity, statistical energy analysis,mechanical mobility techniques,diagnostics using signal energy andsignal phase, and waveform recov­erydiagnostictechniquesareusefuland relatively new concepts innoise and vibration. The book isunique and comes strongly recom­mended.

Michael Norton.

INTER-NOISE 87PROCEEDINGSAcoustical Society of China,PO Box 2712, Beijing,Peoples Republic of China.2 Volumes, 1,692pp.Price: $USBO(includes postage).

These proceedings contain thepre-prints of 412 papers which werepresented at INTER-NOISE 87, the16th International Conference onNoise Control Engineering, andorganised by the Acoustical Societyof China and the Institute of Acous­tics, Academia Sinica. The themeof the Conference was "Noise Con­trolin Industry" and the distributionof the papers in the various cate­gories was: General 1 per cent,Physical Phenomena 4 per cent,Vibration 7 per cent, Immission:Effects of Noise 17 per cent,lmmis­sion: Physical Aspects 12 percent,Requirements 4 per cent, Emission:Noise Sources 17 per cent, NoiseControl Elements 12 per cent andAnalysis 26 per cent.

In the opening address, FritzIngerslev outlined the backgroundto Inter-Noise and the relationshipsbetween the institutes and organi­sations for acoustics, eg, ICA, INCE,ICBEN, IEC Technical Committes,etc. The first plenary lecture wasgiven byJ E Ffowcs Williams fromthe University of Cambridge on"Active Control of Unsteady Flow".The second by R H Lyon from theMassachusetts Institute of Tech­nology on "Conflict Resolution­nology on "Conflict Resolution­Noise Reduction Style". The thirdwas given by D Y Maa from Aca­demia Sinica, Beijing, on "GeneralLaws and Reduction of Aerody­namic Noise".

These papers are then followedby the contributed papers which areincluded within each of the cate­gories listed above. Each paper isonly four pages long so only givesthe main essential concepts. Thevalue of proceedings of this natureis that there is enough data for thereader to assess if the informationis of sufficient interest to warrantfollowing up with personal com­munications. The breadth of topicscovered by the papers also gives

guidance to the current areas ofresearch throughout the world.Inter-Noise has the reputation ofencouraging papers dealing morewith applications than withtheoreti­cal considerations and these pro­ceedings would seem to justify thisreputation. This practical approachis emphasised by the theme of theconference.

The proceedings would be ofinterest to anyone at all involved innoise control in industrial situations.They would be a valuable additiontoanylibraryand,atacostoflessthan 5c (US) per page, representexcellent value.

Marion Burgess

TRANSPORTATION NOISEREFERENCE BOOKP. Nelson (Editor)Butterworths, London, 1987, pp500,ISBN 0-408-01446-6. Australian Dis­tributor: Butterworths Pty Ltd, 271­273 Lane Cove Road, North Ryde,NSW 2113. Price A$220.

This book, exclusively on road,rail and air transport noise, con­tains 24 chapters written by 27authors from six different countries.A recipe for disaster? Not so. Thebreadth of material covered, thedepth of specialist knowledge con­tained in the individual contribu­tions and the impressively strongeditorial control has produced athoroughly readable, and long over­due comprehensive source book onthe generation, assessment andcontrol of transportation noise.

Sections on each of the threetransport modes are structured inthe same way. They begin with thesources of vehicle noise and pos­sible engineering emission controls;then on to factors which influencelevels during vehicle operation andpropogation to the receiver. Pre­diction models and mitigation stra­tegies and wider issues associatedwith noise from each transportationsystem follow. Chapters are alsodevoted to vibration from each ofroad and rail transport. Most chap­ters approach a state-of-the-artreview.

Two-thirds of the 24 chaptersare specific to a transport mode.The remaining chapters provide abasic, but totally adequate, intro­duction to transportation noisemeasurement scales and ratings; asynthesis of findings on communityresponse to transportation noise;and specific reviews of evidence ofthe effects of transportation noiseon health and sleep. An overview

is also provided of different metho­dologies for the environmentalevaluation of transport plans andthere are brief chapters on theevaluation of noise and economicinstruments for transport noiseabatement. The list of referencesand further readings at the end ofeach chapter increase the utilityof the text as a source book.

What sets this book apart fromother acoustic texts is its un­ashamed focus on transportation.Apart from Transport and Environ­ment by Hothersall and Salter andRoad Traffic Noise by Alexandreet ai, neither of which have beenparticularly successful, workers inthe field have had to relyongen­eraltextsontheeffectsorcontrolof environmental noise, on rela­tively small transport related sec­tions in the standard noise controlhandbooks, and on keeping trackof where definitive material ona particular transport topic hadappeared in the technical journals.Much important transport noise in­formation, particularly with respecttoaircraftnoise,hasalsobeenrela­tively inaccessible in government orindustry reports. TransportationNoise Reference Book is a timelysolution to this omission from thebook shelf for what is, afterall,themost widespread pollution problemin urban areas of the developedworld.

The text is comprehensively illus­trated with figures many of whichappear to have been redrawn tostandardise the format across thedifferent chapters. Effective editor­ialcontrol is also evidenced byminimal overlap in the material ofdifferent authors, quite extensivecross referencing between chapterswhere this was appropriate, and aninsistence on at least a commonvocabulary and symbols for themultitude of noise scales. The latterwas no mean achievement andbroke down only a few times.

I was somewhat disappointed thatchapters on noise from marine craftwere not included in the text, par­ticularly as hovercraft, hydrofoilsand recreational craft are frequentlyfound in operation near to residen­tial areas. Noise from "new" urbantransport modes such as monorailvehicles also did not find a place.

It is a book which rio-one withan interest in transportation noiseor transportation managementshould be without-though yourbank manager might not agree. Atleast make sure your library ordersa copy!

Lex Brown.

CI~

ACOUS TIC EDITOR ill ...... ;oc:ous.­

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yat_IhoJ _ .....· inbe . qleC1Od torKOll ....._.ncI_nd reme<lialactlofl.

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Tho 5)'1'. '" l\as beenapecillully lSotigned lori"" uttry .n.cl aClucabonal8f1uatJOn1-.. N hencbonMundaf'ltandino of fflOdl..=:"~ibr.tlorl " ~orod

NEW PUBLICATIONS

JOURNALSAppli ed AcousllcsVOI26, Nos l ,2,3,4 (1989): Vol 27,No 1 (t989).Austr alian J 01 Audiol ogyVol 11. No 1, May 1989Canadian AcousticsVol 17,Nos 1,2 (1989)Chinese J 01Acoustics(Ill Englllh)vo I8,No l(1989).I. INCE NewsletterNo 53 (March 1989).

Includes : INCE d asslficalio" 01 sub­jectsJ Aus! Assoc Muslnstr MakersVol a, No 1 (Ma'ch 19S9).

Contenrs Include: S Merty, Somear>Plica tions 01 mode rn lechnology 10musical Inatrument making: a Alcock &~u~~~~:' A spreadsheet lor siring oa l-

J Catgut Acou stic al SocietyVol 1, No 3 (Seriea II), May 1989Shock & Vibration DigeatVol 21, Nos 1,2,3,4,5 (1989).

The Proceedi ngs will be 01 Inle reSlto eng ineers concllrnlld with noise con­lrol technology, educato rs, ecous tlca lcon eunaoe. gove,nmen t researclle rsand regulators, ooise cont rololllcia ls,and o thers concerned with t.... te ch­nOl09Y 01 no ise conlro l

Copies of the Nois...Con 88 Pro­cee dings are avlliiab le lor$US60 ea chIrom Noise Control Foundatio n, PO Box2469, Arlington Brand', Pough keeps ie,NY 12603, USA. II sh ipmenl OVer5easby air Is des ired, the extra cha rges are$19 per boo k. The book con lains 656printedpag.es

Noise Conlrol Dtlsign: Mel""'ds andPracllce was the theme 01 Noise-Con88,the 1988 Nal ionel Conlerence onNolseConlro IEnglnee rlng.Noise-Con88 was sp oMored by the Inslltute o tNoise Cont rol Er>gineerlng and PurdueUniversity, The mee ting was held 0"lhe Purdue ca mpus On 20-22 J une1986. The Proce ed ing. of Noise-Con 88are now evattable. One hund ' a<!pa perso n a wide va'iety 01 loplcs on noIsecontrol enq ineering appe ar in Ihe Pro­ceedin gs. Top ics inciude fan noise con­" ol, lnle rio. nolsa reduction in eircraf t,abso rplion ot sound In lhe almoSflhere,act ive noise conlrof,lhe ac oustics ofopen plan oUlce. , sou"d powe r deler ­minalion, acous llc holograjl hy andsound lolenslty

Noise-Con 88 Proceed ings

ana lysis and structural dynamics. Ma"yrealis tic examp les and explana.loryillusl,a lions help the roade r to altaln abasic U"d erslandi ng ollhes.e olle napparently complex subjects

Fu' /he r In'ormallon , Bruel &. Kjaer(Aust), 24 Tepko Road, Terrey Hills,NS W 2084. Tel, (02) 4502068 .

surements, charlS the reasons lormak­ingastruclurelal\Qlysls, .surveys thetechniques used fo. meuuong bothlhe

I :~~~~~~~ t~~da;~,rg~t~~~ ~igdn:~r.:ch~~nelFFTanalyse.s

Pari Two, Modal Analysis and Slmu­tation, lakes the reader into the worldof modal le.Hog , wllh ils spac iallsedtech niques and C<lmputer software . Aslep_by_step exampl e 01 a modal tealcha rls lho prOduction 01 a dynamIcmOdal mOdel and ilS subseq uent app"·~i'::.i~I~I;~~S respoose and modlficallon

Structural Testlng­A Two-part Primer

Noise & Vibration ControlL Ber an ek

A

What Is a mobility measmemenl ? Amobilily matrix? Quad,a ture picking ?MOde shajle? What is an ope1811008.Idelledlon shapa? A modal modal?eu .......fitting? Whal are pole locatio"end residue? Where is the mOdal­Si>l!Ce? Why make a mOdal analysis ?The answers 10 these and many olherQueslions are all give" in "Slruct uralTes ting", Ihe rete st _ lwo-part ­prlmer lrom BrlJel & Kjaer

Part One, Mechanica l Mobility Mea -

:I::~~y ar~h~I~~t~~'g "ee~~~I~~~tsr'es:~;~~:Elf$ , publicofllcials and olhera con ­camed wllt'lhe con trol olnois" emine dby machinery and wilh conl,o l 01 en­vironmenlal noise in bolldlllgS. In Ih"W<lrkplace,n(>ar ai rports and highwaY",and in Ike co mmunity. This revi. edecnc e nae bae" updal"d 10 i"c ludemodern methods for the dete rmination01 machinery noise emiss ion, end Ihech epter en noise cmerte has bee"comp leloly rovised to reflect c riteria"'rconlrol cl building air sySlem noiseand orite ria loreonlrol 0' noise aroundhighwar.; and Mound airports

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The 0$-417 Is Ihe newesl membe'of Instanlel's complete lamily or port­able blasl monilora and analyse,". The05--477 provides instanl documenle dana lysis o f ground vibration and air~.tlnaportable,seIH::onlai""dPack-

The unll o fle rs many lea1l,,'es Includ­Ing: oocumeme c alld comprehen siveanalY"is capability , inSlanlanalysis, low

rJ',erf~~~~ c~~~a~~~m~nT.°dTi:.r ~me~eas y 10 ope .a te by any use ., end meetsme requ irements lor 'eUabll lty rugged­ness and portability de manded in theAuslralia" environmenl

Fu,the r Inlormatlon : VIP6c, 275-283NfJfmanby Fload, Port Melbourne, ViC.,3207. Phone (03) 647 9700.

Quarle rl, Progr. .. and Sialua ReportRoyal Ins tilutio" 01 Technology,

Stockho lm, 1/ 1989 (May 1989).Thls ls.ue conla ins t.... proceedl r>gs

01 Fonelik-89.lhe 3rd aMua l Swed ishphonetic s sym~sium

NaUo","l Acolls!ic "'boratori..Report 122: J Macrae, Dete rioration

01 hearing associa ted with hearing atdUM, Australian Government PublishingServic e,Canbe rrap9a9) .

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~o~~~~~ v:'ia~:~iC%:t7~ i~g::,s,:~bjt:ary, even with the sound turned uploud, with racin9 in progress.

(il) Moderate IntrusionA speech interference level be­tween 43 dB and 49 dB, te, whereit would be difficult to tollow theradio or TV set to normal listening.

(iii) Properties where the effect of therace would not intrude into normalactivities

ie,wherespeechinterferencelevelsin this region would be below43 dB with racing in progress.

A map was drawn indicating thedegree of intrusion. It was evident thatalmost all of those likely to experiencethe greatest level of noise had a firstclass view of the racing and were at thecentre of what many considered to bethe most spectacular spectator sportingevent Birmingham had to offer. Experi­ence showed that many chose to watchthe racing rather than stay indoors.

It is worthy of note with peak soundleveis recorded between 119 dB (A) and125dB(A) at various points around thethe circuit, the only complaint receivedby the Environmental Services Depart­ment related to early morning repairs toIhe safety barriers occasioned by over­night vandalism.

(Extracted fromLondon Environmental Bulletin,

4(4),1988), ========

One of the environmental aspectsconsidered prior to the staging of the

~i~: B~~~~~tr~~I;eu~~r ::~~ ~~s ~~r~te~:

Noise versus View

The circuit is approximately 2V2miles long and Includes part of twomain arterial roads, both of which havehigh rise dwclllnqs along one side andpart of the inner city ring road whichpasses through areas of both high andlow rise housing. Many of the dwellingsin the vicinity of the circuit are exposeddaily to high levels of traffic noise and,indeed, many have been provided withnoise insulating double glazing underthe provisions of the Noise InsulationRegulations 1975. Nevertheless, it wasclear from previous assessments madein 1984, when motor racing trials wereheld to jUdge the suitability of the cir­cuit, that noise would be a significantfactor. Many of the vehicles, particularlythose taking part in the Formula 3000event, have high performance enginesand no silencing.

Based upon measurements and cal­culation, the houses around the circuitwere placed into three categories,. asfollows:-

(i)SignlficantiyAffected

Where speech interterencer tevetwould exceed 49 dB, ie, where it

Publications by Australians

1987

On the Insertion Losses Produced byPlane Acoustic Lagging StructuresA C K AU, K P BYRNESchool of MechanIcal and IndustrialEngineering, The University of New~~~h20~~~es, PO Box 1, Kensington,

J Acoust Soc AM 82(4), 1325-1333(1987).

Theory of Twin-Core Optical Fibre Fre­quencyShifterP L CHU, AW SNYERSchool of EI Eng & Computer Sciences,The University of New South Wales, POBox- 1, Kensington, NSW 2033.Electronics Letters 23(21), 1101-1102(1987).

Phase Spec1ral Evidence for VortexStructures In Turbulent MixingM R DAVISDept of Civil and Mechanical Eng, Uni­versity of Tasmania, Hobart, Tas 7001.J Sound Vib 116(2),303-321 (1987).

A Coincidence Damper for ReducingPipe Wall Vibrations in Piping Systemswith Disturbed Internal Turbulent FlowI. M. HOWARD, M. P. NORTON, B. J.STONEDept. of Mechanical Enq., University 01Western Australia, Nedlands, W.A.6009J. SoundVib. 113(2),377-393 (1987).

Community Response to Noise: A Rs­view of Factors Inlluenclng the Relation-

~~i~ :e:::en Noise Exposure and Reac-

Dept of Psychology, University of Syd­ney, NSW 2006.J Acoust Soc Am 83(4), 1325-1333(1987).

The Ellects of a Face Interview Versusa Group Administered Questionnaire inDetermining Reaction to Noise in theWorkplace •(1) R. F. S. JOB(2}R.B.BULLEN(1) Dept. ot Psychology, Sydney UnIver­sity, N.S.W. 2006J. Sound Vib. 116(1),161-168 (1987).

Acoustic Scattering from an ArbitrarilyRough SurfaceB J KACHOYAN, C MACASKILLDept of Appl Mathematics, University ofSydney, NSW2006.J Acoust Soc Am 82(5), 1720-1726(1987).

Fun with Missing FundamentalsT. M. KALOTAS, A. R. LEEDept. of Physics, La Trobe UnIversity,Bundoora, VIC. 3083Am. J. Physics 55 (2), 184 (1987).

A Comparison of Modal Density Meas­urementTechniquesP R KESWICK, M P NORTONDept of Mech Eng, University of WesternAustralia, Nedlands, WA 6009.Appl Ac 20(2),137-153 (1987).

Vol. 17 No. 2-52

Non-Linear Mode Coupling In Symmet­ricallyKfnkedBars .K A LEGGE, N H FLETCHERDept of Physics, University of NewEngland, Armidale, NSW 2351.J SoundVib118(1),23-24 (1987).

Generalisation of fhe Method for theEstimation of the Frequencies of Tonesin Noise from the Phases of DiscreteFourier TransformsD. R. A. McMAHON, R. F. BARREnWeapons Systems Res. Laboratory, Def­ence Science and Technology OrganI­sation, Defence Res. Centre, Salisbury,G.P.O. Box 215, Adelaide, S.A. 5001Signal Processing 12(4),371-383 (1987).

Young's Modulus and Shear Modulus ofa Composite Shaft from ResonanceMeasurementsA. SPENCERResearch Establishment, AAEC, LucasHeights, PrivateMall Bag, Sutherland,N.S.W., 2232Composites Science Technology 28 (3),173-191 (1987).

Modelling of Structure-Born Noise InVehicles with Four-Cylinder MotorsJ K VETHACAN, L A WOODDept of Civil and Aeronautical Eng,~!J!ji: GPO Box 2476V, Melbourne, VIc

IntJofVehicleDesign8(4/5/8),439­454(1987).

1988

The Properties of Wood and MusicalInstrumentsK BAMBERJAAMIM 7, 3, No 33 (Dec 88).

Kosters Prism Time-Integrating Acusto­Optic CorrelatorM S BROWNDefence Science and TechnologyOrganisation, Dept of Defence, Ade­laIde, SA 5001.J Physics E: Scientific Instr21(5),192­194(1988).

~hg~~E~~rXli~~nsSuperior?

20 Dryandra Street, O'Connor 2601.JAAMIM 7,22, No 1 (Mar 88).

The Variance of Decay Rates at Low

~r~q~:~es~f~~O Divn Bldg Constrn & Eng, Highett

Appl Ac 23(1), 63 (1988).

The Effect of Moving Microphones andRotating Diffusers on the Variance 01Decay RateJ LDAVY, I P DUNNDiv of BUilding Research, CSIRO, POBox 56, Highett, Vic 3190.Appl Ac 24(1), 1-14 (1988).

~~o~~~L~r~perties 01 Timber

foCnh~~~~.f Physics, Univ NSW, Kensing­

JAAMIM 7, 11, N03 (Dec 88).

Obliquely Truncsted Simple Horns:Idealized Models for Vertebrate Pinnae(1) N H FLETCHER(2) S THWAITES(1) Inst of Physical Sc, CS/RO, -Ume­stone Avenue, Canberra, ACT 2602.Acustica 65(4),194-204 (1988).

Dispersion of Waves In Piano StringsM PDLESAK, A R LEEPhysics Dept, La Trobe University, Bun­doora, Vic 3083.J Acoust Soc Am 83(1),305-317 (1988).

Can Sound Quality be Measured?H F POLLARDSchool of Physics, Univ NSW, Kensing­ton 2033.JAAMIM 7, 8, No 2 (Oct 88).

On Estimating the Instantaneous Fre­quency of a Gaussian Random Signalby Use of the Wigner-Ville DistributionL B WHITE, B BOAI:lASHDept. of Electrical Eng, CRISSP, Univer­sity of Queensland, Brisbane, Qld 4067.IEEEA Trans on Ac, Speech and SignalProcessing 36(3),417-420 (1988).

NATIONAL ACOUSTICLABORATORIES

HELPING PEOPLE HEAROPEN DAY

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FUTURE ElJENT5 ~

1989

August 6-10, PRAGUEXX 1st CONGRESS OF INTERNATIONALASSOCIATION OF LOGOPEDICS ANDPHONIATRICSDetails: IALP 1989, c/- CzechDslDvakMedical SDciety, J E Purkyne, MrsLudmila Fortove, Vitezneho unora 31,CS-12026 Prague 2.

• August 8-10, SYDNEYCOMPUTING SYSTEMS ANDINFORMATION TECHNOLOGY 1989Details: Conference Manager, Institutionof Engineers, 11 NatiDnai Circuit, Bar­ton, ACT 2600.

August 16·18, SINGAPOREINTERNATIONAL CONFERENCENOISE & VIBRATION 89Details: The Secretariat, InternationalConference Noise & Vibration 89, cl­SChODf ot Mechanicaf & ProductionEngineering, Nanyang TechnologicalInstitute, NanyangAve., Singapore 2263.

August 19-22, MITTENWALDINTERNATIONAL SYMPOSIUM ONMUSICAL ACOUSTICSDetails: Sekretariat des ISMA 1989, cl­Muller-BBM, Robert-Koch-Str 11, 8033Pfanegg, W. Germany.

August 24-31, BELGRADE13th ICASYMPOSIA

September 1-3, ZAGREBElectrDacDustics

~::t::~:;;c~-6, DUBROVNIK

Details: 13 ICA Secretariat, SavaCentre, 11070 Belgrade, YugDs/avia.

September 5-7, OXFORD5th INTERNATIONAL MEETING ONW~ FREQUENCY NOISE AND VIBRA-

Details: Multi-Science Publishing CDLtd, 107 High Street, BrentwoDd, EssexCM14 4RX, UK.

September 26-28, PARISEUROSPEECH 89Details: D. Bovis, ESCA Secretary,EEC-DG XIII/ESPRIT, 25 Rue Archi­mede, Brussels, Belgium.

October 3-6, HIGH TATRA28th CONFERENCE ON PHYSIOLO­GICAL ACOUSTICS, ACOUSTICS OFSPEECH AND MUSICDetails: House 01 TechnDIDgy, Eng LGoralikova, Skultetyhd ul, 83227 Brat­islava, Czechoslovski«.

October 4-6, MONTREALIEEE/UFFCSUltrasonics svmpcetum.Details: Allied-Signal Inc., Atten.: H.van de Vaart, PO Box 10221R, Morris­town, NJ 07960, USA.

October 16-18, SICtLYINTERNATIONAL CONFERENCE ONMONITORING, SURVEILLANCE ANDPREDICTIVE MAINTENANCE OFPLANTS AND STRUCTUREDetails: Italian Society IDr Nondestruc­tive Testing, via Arnalda Forest; No.5,25126 Brescia, Italy.

October 17-19, KYOTOINTERNATIONAL CONFERENCE ON

~~~~~TI~~RCEPTION AND

Details: ICMPC Secretariat, Dept Music,KYDtD City University of Arts, Kutsu­kake, Ohe, Nishikyo-ku, KYDtD, 610-11Japan.

October 18-19, BARCELONAII WORLD CONGRESS OFCHRONICAL RONCOPATHY"Snore and OSAS Syndrome."Details: Prof. E. Perella, Facultat deMedicina, UniversitatAutonoma de Bar­celona, Passeig de la Vall D'Hebron,S/N08035 BarcelDna, Spain.

November 14-16, ADELAIDE• AUSTRALIAN INSTRUMENTATIONAND MEASUREMENT CONFERENCEDetails: The Conterence Manager, AIM89, The Institution of Engineers, Aus­g:3;: 11 National Circuit, Barton, ACT

November 15-17, BILBAOINTERNATIONAL SESSIONS ON THESINGING VOICEDetails: PO Box 1346, 48080 Bilbao,Spain.

November 23-24, PERTH• 1989 AAS CONFERENCElnterlor NDise Climates.Details: C. Paige, C/- BHP Engineer-

~!61 2JZstr~~ia.Georges Terrace, Perth

November 26-29, CANBERRA• 1989 ERGONOMICS SOCIETY OFAUSTRALIA CONFERENCEErgDnDmics, Technology & ProductivityDetails: Beth Steward, ACTS, Suite 2,BMI Building, City Walk, Canberra,ACT,2601.

Nov 27-Dec 1, ST LOUISMEETING OF ACOUSTICAL SOCIETYOF AMERICADeteils: Murray Strasberg, ASA, 500Sunnyside Blvd., WDodbury, New York11797, USA.

December 4-6, NEWPORT BEACHINTER-NOISE 89

~~?~~E~~~~cfC'R ENVIRONMENTAL

Details: tnter-noise 89, PO Box 2469,Arlington Branch, Poughkeepsie, NY12603, USA.

December 10-15, SAN FRANCISCOINTERNATIONAL SYMPOSIUM ON~~~I~~llg~L METHODS IN ACOUSTIC

Details: Pro! R J Bernhard, Ray WHerrick Labs, SChDDI of Mech Eng,:~~~~~ University, West Lafayette, IN

December 11-12, RIO DE JANEIRO3rd INTERNATIONAL SEMINAR ONNOISE CONTROLDetails: Organising Committee, Labora­torio de Acustlca e Vtbracoes, Pem­Coppe/UFRJ, C.P.68503, 21.945, Riode Janeiro, Brazil.

1990

February 13-15, LEIPZIG4th CONFERENCE ON HYDRO- ANDGEOACOUSTICSDetails: Dr Wendt, Wilhelm-Pieck-Univer­sitat Bostock, Sektion Technische Elek­troink,AlbertEinsteinStrasse2,RDs­tack, GDR-2500.

April 17-20, VIENNADAGA 90Details: DAGA.

May 21-25, PENNSYLVAN~A

~~EI~NE~lg ACOUSTICAL SOCIETY

Details: Murray Strasberg, ASA, 500Sunnyside Blvd., Woodbury, New York11797, USA.

June 6-8, BRIGHTON (UK)16th CONGRESS OF A ICBThe FulureforNoiseControl-1owardsaninlerdisciplinaryapproach.Details: Dr. iur. Willy Aecherli, Recht­sanwalt Hlrschenplatz 7, CH-6004,Luzern, Switzerland.

August 1-6, GOTHENBURGINTERNOISE 90Details: Swedish Road and Traffic Re­search Institute, S-58101 Linkoeping,Sweden.

August 8-10, GOTHENBURGINTERNATIONAL TIRE/ROAD NOISECONFERENCE.Details: Intern. Tire/Road Noise Con­ference, C/- Sandberg, Swedish Roadand Traffic Research Institute, S-581 01Linkoeping, Sweden.

• September 18-20, MELBOURNEVIBRATION & NOISE CONFERENCEDetails: L Koss, Dept Mech Eng, MonashUniversity, Clayton, Melbourne, Vic,3168.

November 26-30, SAN DIEGO

~~e.I~~~lg: ACOUSTICAL SOCIETY

Details: Fredrick Fisher, Marine PhysicalLab, P-001, Scripps Institute oceanc­graphy, Univ California, San Diego, LaJolla, CA92093-0701, USA.

1991

• November, BRISBANEWESTERN PACIFIC REGIONAL ACOUS­TICS CONFERENCE IVDetails: Unisearch Ltd, PO Box 1, Ken­sington, NSW2033.

O"CTOO'/"'" 0Ll-,l,cTI'-"L 5-0"'.--'LI"L'_" ',"L ru) 1'-- _'_"ILn _ LC -'

1989 ANNUAL CONFERENCEPERTH, WESTERN AUSTRALIA

23-24 NOVEMBER, 1989Venue: Cottesloe Beach Resort, Perth.Theme: "Interior Noise Climates".

For-MusicTravel'CommunicationOffice WorkIndustrial Workor just Plain Relaxation,

Interior noise climates are of interest to a wide range of acousticians.A varied and interesting programme consisting of keynote -addresses,papers, workshops and a site visit is being arranged.Dr Ragnar Rylander is an invited keynote speaker.Watch the sun set over the Indian Ocean from the Cottesloe BeachResort, just a stone's throw from one of Perth's favourite beaches.

Further Information: AAS 1989 Conference SecretaryPO Box 5077Cloisters Square, Perth 6000

Phone: Mr Clive Paige (09) 4265700

SUSTAINING MEMBERS

K. H. STRAMIT LTD.52 MANDOON ROADGIRRAWEEN 2145

RICHARDSON PACIFICSOUND CONTROL

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UNIT 7,2 STANTON ROADSEVEN HILLS 2147

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C/- SCIENCE CENTRE35 CLARENCE STREETSYDNEY, N.S.W. 2000

BORAL AUSTRALIAN GYPSUM676 LORIMER STREETPORT MELBOURNE, VIC. 3207

C.S.R. LTD. BRADFORDINSULATION GROUP

12 MOUNT STREETNORTH SYDNEY 2060

BRUEL & KJAER (AUST.) PTY. LTD. JAMES HARDIE INDUSTRIES LTD.24 TEPKO ROAD G.P.O. BOX 3935TERREY HILLS, N.S.W. 2084 SYDNEY 2001

BHP STEEL INTERNATIONAL NAP SILENTFLO PTY. LT'D.COATED PRODUCTS DIVISIONP.O. BOX 77 51 NORFOLK STREETPORT KEMBLA, N.S.W. 2505 GLEN WAVERLEY 3150

CMA FOAM GROUP ~~~C~/~~~~~~R~~6 ~~~~~~D.1 HEATHCOTE ROAD REVESBY, N.S.W. 2212LIVERPOOL, N.S.W. 2170

THE CHADWICK GROUP292 BURNS BAY ROADLANE COVE 2066

FOAMLITE AUSTRALIA PTY. LTD. SOUNDGUARD PTY. LTD.P.O. BOX 331 Division of PyrotekSUNNYBANK, OLD. 4109 ~~Jl:~~~~ES~f1~ET

INDUSTRIAL NOISE CONTROLPTY.I,.TD.

22 CLEELAND ROADOAKLEIGHSOUTH 3167