THU NAMA UTAN ATAU TAMA NA UITATE

THU NAMA UTAN ATAU TAMA NA UITATE US010034081B2

( 12 ) United States Patent Tipparaju et al .

( 10 ) Patent No . : US 10 , 034 , 081 B2 ( 45 ) Date of Patent : Jul . 24 , 2018

( 54 ) ACOUSTIC FILTER FOR OMNIDIRECTIONAL LOUDSPEAKER

( 56 ) References Cited U . S . PATENT DOCUMENTS

@ ( 71 ) Applicant : Samsung Electronics Co . , Ltd . , Suwon - si , Gyeonggi - do ( KR )

@ . . . . . . . . .

( 72 ) Inventors : Lakshmikanth Tipparaju , Valencia , CA ( US ) ; Allan Devantier , Newhall , CA ( US ) ; William Decanio , Valencia , CA ( US ) ; Andri Bezzola , Pasadena , CA ( US )

3 , 649 , 776 A 3 / 1972 Burton 3 , 912 , 866 A * 10 / 1975 Fox . . . . . . . . . . . . . . . . . . . . . . H04R 1 / 2865

181 / 155 4 , 157 , 741 A 6 / 1979 Goldwater 4 , 322 , 578 A * 3 / 1982 Selmin H04R 1 / 345

181 / 175 4 , 336 , 861 A 6 / 1982 Peter 4 , 348 , 549 A * 9 / 1982 Berlant H04R 1 / 26

181 / 152 4 , 348 , 750 A 9 / 1982 Schwind 4 , 876 , 723 A 10 / 1989 Fang

( Continued ) @ ( 73 ) Assignee : Samsung Electronics Co . , Ltd . ,

Suwon - si ( KR )

( * ) Notice : FOREIGN PATENT DOCUMENTS Subject to any disclaimer , the term of this patent is extended or adjusted under 35 U . S . C . 154 ( b ) by 0 days .

JP 0485284 A15 / 1992

2004343229 A 12 / 2004 ( Continued ) ( 21 ) Appl . No . : 15 / 141 , 594

( 22 ) Filed : Apr . 28 , 2016 OTHER PUBLICATIONS ( 65 ) Prior Publication Data

US 2017 / 0094403 A1 Mar . 30 , 2017 International Search Report and Written Opinion dated Dec . 29 , 2016 for International Application No . PCT / KR2016 / 010650 from Korean Intellectual Property Office , pp . 1 - 12 , Daejeon , Republic of Korea .

( Continued ) Related U . S . Application Data ( 60 ) Provisional application No . 62 / 233 , 927 , filed on Sep .

28 , 2015 . ( 51 )

( 52 )

Int . Cl . H04R 1 / 28 ( 2006 . 01 ) U . S . CI . CPC . . . . . . . H04R 1 / 288 ( 2013 . 01 ) ; H04R 2201 / 029

( 2013 . 01 ) Field of Classification Search CPC . . . . . . H04R 1 / 30 ; H04R 1 / 345 ; HO4R 2201 / 34 See application file for complete search history .

Primary Examiner — Matthew Eason ( 74 ) Attorney , Agent , or Firm — Sherman IP LLP ; Kenneth L . Sherman ; Hemavathy Perumal ( 57 ) ABSTRACT One embodiment provides an omnidirectional loudspeaker comprising a phase plug and an acoustic resonator within the phase plug . The acoustic resonator comprises acoustic damping material .

20 Claims , 21 Drawing Sheets

( 58 )

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( 56 ) References Cited U . S . PATENT DOCUMENTS

5 , 115 , 882 A * 5 / 1992 Woody . . . . . . . . . . . . . . . . . . . . . . HO4R 1 / 345 181 / 144

5 , 261 , 006 A 11 / 1993 Nieuwendijk et al . 5 , 306 , 880 A 4 / 1994 Cozair et al . 5 , 451 , 726 A 9 / 1995 Haugum 5 , 521 , 983 A 5 / 1996 Thompson et al . 5 , 673 , 329 A 9 / 1997 Wiener 5 , 886 , 304 A 3 / 1999 Schlenzig 5 , 952 , 620 A 9 / 1999 Hamilton 5 , 995 , 634 A 11 / 1999 Zwolski 6 , 009 , 972 A 1 / 2000 Choi et al . 6 , 026 , 928 A * 2 / 2000 Maharaj . . . . . . . . . . . HO4R 1 / 30

181 / 152 6 , 785 , 397 B2 8 / 2004 Arnstein 6 , 820 , 718 B2 11 / 2004 Lacarrubba 6 , 950 , 530 B2 9 / 2005 Baird et al . 7 , 236 , 606 B2 6 / 2007 Werner 7 , 587 , 227 B2 9 / 2009 Cheung 7 , 614 , 479 B2 11 / 2009 Plummer 7 , 920 , 712 B2 4 / 2011 Butler 8 , 014 , 545 B2 9 / 2011 Grant 8 , 027 , 500 B2 9 / 2011 Fincham 8 , 081 , 766 B2 12 / 2011 Gunness 8 , 116 , 500 B2 2 / 2012 Oxford et al . 8 , 121 , 330 B2 2 / 2012 Dodd et al . 8 , 130 , 994 B2 * 3 / 2012 Button H04R 1 / 24

181 / 155 8 , 181 , 736 B2 5 / 2012 Sterling et al . 8 , 199 , 953 B2 6 / 2012 Buccafusca 8 , 280 , 091 B2 10 / 2012 Voishvillo 8 , 290 , 195 B2 * 10 / 2012 Chick H04R 1 / 36

181 / 175 8 , 418 , 802 B2 * 4 / 2013 Sterling . . . . . . . . . . . . . . . H04R 1 / 2803

181 / 176 8 , 428 , 284 B2 4 / 2013 Meyer et al .

8 , 467 , 557 B2 * 6 / 2013 Miller . . . . . HO4R 1 / 24 381 / 182

8 , 638 , 959 B1 1 / 2014 Hall 8 , 672 , 088 B2 * 3 / 2014 Sterling . . . . . . . . . . . . . . . H04R 1 / 2803

181 / 176 8 , 750 , 540 B2 * 6 / 2014 Tan . . . . . . . . . . H04R 1 / 345

181 / 144 8 , 857 , 559 B2 10 / 2014 Reviel 8 , 873 , 787 B2 10 / 2014 Bergere 9 , 060 , 219 B2 6 / 2015 Guenther 9 , 173 , 018 B2 10 / 2015 Silver et al . 9 , 282 , 398 B2 * 3 / 2016 Monroe . . . H04R 1 / 22 9 , 549 , 242 B2 1 / 2017 Silver et al .

2002 / 0118858 AL 8 / 2002 White 2005 / 0175207 Al 8 / 2005 Alexander et al . 2008 / 0107291 Al 5 / 2008 Livingston 2008 / 0192972 A1 * 8 / 2008 Lewallen . . . . . . . . . . . . . . H04R 23 / 00 H04R 23 / 00

381 / 343 2010 / 0027833 AL 2 / 2010 Takahashi 2011 / 0019854 A1 1 / 2011 Graber 2012 / 0219171 Al 8 / 2012 Velican 2013 / 0228393 AL 9 / 2013 Sterling et al . 2014 / 0003645 A1 1 / 2014 Silver et al . 2014 / 0029781 A11 / 2014 Valtchev et al . 2014 / 0185854 A1 7 / 2014 Murphy 20160227315 Al * 8 / 2016 Kim . . . . . H04R 1 / 2819 2017 / 0094406 AL 3 / 2017 Bezzola

FOREIGN PATENT DOCUMENTS . . . . . . . . . . . . . . . KR

Wo 101510692 B14 / 2015

2015094115 Al 6 / 2015

OTHER PUBLICATIONS . . . . . . . . . . . . . . . . . . . . . .

U . S . Restriction Requirement for U . S . Appl . No . 15 / 141 , 594 , dated Mar . 12 , 2018 by Examiner Huyen D . Le .

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Identify Resonances in a Cavity of an Omnidirectional Loudspeaker to Remove con 801

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Determine At Least One Phase Plug Property Suitable for Removing Acoustic Amplification Generated by the Resonances Based on an Application and a Size of

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Fabricate a Phase Plug for Removing the Acoustic Amplification Based on the At Least One Phase Plug Property , wherein the Phase Plug Comprises an Acoustic

Resonator Including Acoustic Damping Material

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Position a Portion of the Phase Plug Directly Across From a Radiating Surface of the Loudspeaker in the Path of Sound Propagation

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Remove Acoustic Amplification Generated By Resonances in a 902

Cavity Between a Diaphragm and a Phase Plug of the Loudspeaker by Attenuating , Utilizing an Acoustic Resonator of the Phase Plug ,

the Sound At a Pre - selected Frequency

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US 10 , 034 , 081 B2

ACOUSTIC FILTER FOR FIG . 3 illustrates a cross - section of an example modified OMNIDIRECTIONAL LOUDSPEAKER phase plug for an omnidirectional loudspeaker , in accor

dance with an embodiment . CROSS - REFERENCE TO RELATED FIG . 4 is an example graph illustrating multiple frequency

APPLICATIONS 5 response curves , in accordance with one embodiment . FIG . 5A illustrates a cross - section of another example

The present application claims priority to U . S . Provisional modified phase plug for an omnidirectional loudspeaker , Patent Application No . 62 / 233 , 927 , filed on Sep . 28 , 2015 . wherein the modified phase plug includes a flat shaped Further , the present application is related to commonly absorber without a perforated plate , in accordance with an assigned , co - pending U . S . Non - Provisional patent applica - " embodiment . tion Serial No . 15 / 141 , 161 , filed on Apr . 28 , 2016 entitled FIG . 5B illustrates a cross - section of another example “ THREE HUNDRED AND SIXTY DEGREE HORN FOR modified phase plug for an omnidirectional loudspeaker , OMNIDIRECTIONAL LOUDSPEAKER ” , filed on the wherein the modified phase plug includes a flat shaped same day as the present application . Both patent applications 15 absorber with a perforated plate , in accordance with an are hereby incorporated by reference in its entirety . embodiment .

FIG . 5C illustrates a cross - section of another example TECHNICAL FIELD modified phase plug for an omnidirectional loudspeaker ,

wherein the modified phase plug includes a curved shaped One or more embodiments relate generally to loudspeak - 20 absorber without a perforated plate , in accordance with an

ers , and in particular , a physical acoustic filter for an embodiment . omnidirectional loudspeaker . FIG . 5D illustrates a cross - section of another example

modified phase plug for an omnidirectional loudspeaker , BACKGROUND wherein the modified phase plug includes a curved shaped 25 absorber with a perforated plate , in accordance with an

A loudspeaker reproduces audio when connected to a embodiment . receiver ( e . g . , a stereo receiver , a surround receiver , etc . ) , a FIG . 5E is another example graph illustrating multiple television ( TV ) set , a radio , a music player , an electronic frequency response curves , in accordance with one embodi sound producing device ( e . g . , a smartphone ) , video players , ment . etc . A loudspeaker may comprise a speaker cone , a horn or 30 FIG . 5F illustrates a top view of an example modified another type of device that forwards most of the audio phase plug for an omnidirectional loudspeaker , wherein the reproduced towards the front of the loudspeaker . modified phase plug includes a curved shaped absorber with

a perforated plate , in accordance with an embodiment . SUMMARY FIG . 5G illustrates a top view of an example modified

35 phase plug for an omnidirectional loudspeaker , wherein the One embodiment provides an omnidirectional loud - modified phase plug includes a flat shaped absorber with a

speaker comprising a phase plug and an acoustic resonator perforated plate , in accordance with an embodiment . within the phase plug . The acoustic resonator comprises FIG . 5H illustrates sound pressure wave fronts around an acoustic damping material . omnidirectional loudspeaker in operation , in accordance

Another embodiment provides a method for producing a 40 with an embodiment . phase plug for an omnidirectional loudspeaker . The method FIG . 6A illustrates a cross - section of an example protrud comprises identifying resonances in a cavity of the omnidi - ing phase plug for an omnidirectional loudspeaker , in accor rectional loudspeaker to remove and fabricate a phase plug dance with an embodiment . for removing acoustic amplification generated by the reso FIG . 6B illustrates a cross - section of an example protrud nances . The phase plug comprises an acoustic resonator 45 ing phase plug for an omnidirectional loudspeaker , in accor including acoustic damping material . dance with an embodiment . One embodiment provides a method for removing acous FIG . 6C is another example graph illustrating multiple

tic amplification in a cavity between a diaphragm and a frequency response curves , in accordance with one embodi phase plug of an omnidirectional loudspeaker . The method ment . comprises generating , utilizing a sound source of the omni - 50 FIG . 6D illustrates a cross - section of the protruding phase directional loudspeaker , sound and removing acoustic plug with a perforated plate , in accordance with an embodi amplification generated by resonances in the cavity by ment . attenuating , utilizing an acoustic resonator of the phase plug , FIG . 6E illustrates a cross - section of the protruding phase the sound at a pre - selected frequency . The acoustic resonator plug with a perforated plate and an extended absorber , in comprises an acoustic damping material . 55 accordance with an embodiment .

These and other features , aspects and advantages of the FIG . 6F illustrates a cross - section of the protruding phase one or more embodiments will become understood with plug with an extended absorber and without a perforated reference to the following description , appended claims and plate , in accordance with an embodiment . accompanying figures . FIG . 6G each illustrate a cross - section of an example

60 protruding phase plug for an omnidirectional loudspeaker , in BRIEF DESCRIPTION OF THE DRAWINGS accordance with an embodiment .

FIG . 6H illustrates a cross - section of the protruding phase FIG . 1 illustrates an exemplary cross - section of an omni - plug with a perforated plate , in accordance with an embodi

directional loudspeaker . ment . FIG . 2 illustrates a cross - section of an example modified 65 FIG . 7A illustrates a cross - section of an example modified

phase plug for an omnidirectional loudspeaker , in accor - phase plug comprising a cylindrical shaped resonator , in dance with an embodiment . accordance with an embodiment .

US 10 , 034 , 081 B2

FIG . 7B illustrates a cross - section of an example modified 118 is positioned at a top section 100B of the loudspeaker phase plug comprising a spherical shaped resonator , in 100 . The first enclosure 102 is positioned in between the accordance with an embodiment . second enclosure 118 and the phase plug 105 . A cavity ( i . e . ,

FIG . 7C illustrates a cross - section of an example modified a gap ) 109 separates a bottom section of the first enclosure phase plug comprising a Helmholtz resonator , in accordance 5 102 and a top section of the phase plug 105 . with an embodiment . A sound source is disposed within the first enclosure 102 .

FIG . 7D illustrates a cross - section of an example modified In one embodiment , the sound source comprises a woofer phase plug comprising a rectangular prism shaped resonator , loudspeaker driver 103 . In another embodiment , the sound in accordance with an embodiment . source comprises a tweeter loudspeaker driver 119 posi

FIG . 7E illustrates a cross - section of an example modified 10 tioned / mounted axially inside the first enclosure 102 or the phase plug comprising an irregular shaped resonator , in second enclosure 118 . accordance with an embodiment . The first enclosure 102 further comprises a diaphragm

FIG . 8 is an example flowchart of a manufacturing 106 and a transducer 107 . With reference to FIG . 6A , the process for producing a phase plug for an omnidirectional transducer 107 comprises a motor structure 51 , a voice coil loudspeaker , in accordance with an embodiment of the 15 53 , a voice coil former 55 , a spider structure 50 , a surround invention . structure 54 , and a frame structure 52 . The loudspeaker 100

FIG . 9 is an example flowchart for removing acoustic reproduces audio ( i . e . , emits sound ) only when it is powered amplification in a cavity between a diaphragm and a phase on . The diaphragm 106 is an example radiating surface that plug of an omnidirectional loudspeaker , in accordance with vibrates when the loudspeaker 100 is reproducing audio . an embodiment of the invention . 20 When the loudspeaker 100 is not reproducing audio , the

diaphragm 106 is at a rest position , as shown in FIG . 1 . A DETAILED DESCRIPTION region 106S of space separates the diaphragm 106 and the

transducer 107 . A portion of the phase plug 105 is positioned The following description is made for the purpose of directly across from the diaphragm 106 , in the path of sound

illustrating the general principles of one or more embodi - 25 propagation . ments and is not meant to limit the inventive concepts During reproduction of audio , the loudspeaker 100 may claimed herein . Further , particular features described herein exhibit large peaks and dips in frequency response curves can be used in combination with other described features in due to resonances in the cavity 109 . Resonances are typi each of the various possible combinations and permutations . cally equalized using conventional methods such as Digital The term " on " includes when components or elements are in 30 Signal Processing ( DSP ) , equalization circuits , etc . These physical contact and also when components or elements are conventional methods , however , are ineffective at removing separated by one or more intervening components or ele resonances in the cavity 109 . Instead , these conventional ments . Unless otherwise specifically defined herein , all methods attenuate a signal going into the loudspeaker 100 at terms are to be given their broadest possible interpretation frequencies of the resonances in the cavity 109 . The reso including meanings implied from the specification as well as 35 nances in the cavity 109 act as an acoustic amplifier that meanings understood by those skilled in the art and / or as re - amplifies the attenuated signal to a desired level . There defined in dictionaries , treatises , etc . fore , distortion components in a frequency region around the

One or more embodiments relate generally to loudspeak - resonances in the cavity 109 are amplified by the resonances ers , and in particular , a physical acoustic filter for an but are not attenuated by an equalizer , thereby negatively omnidirectional loudspeaker . One embodiment provides an 40 impacting sound quality of the loudspeaker 100 . omnidirectional loudspeaker comprising a phase plug and an One or more embodiments of the invention provide a acoustic resonator within the phase plug . The acoustic physical acoustic filter for a loudspeaker providing omnidi resonator comprises acoustic damping material . rectional sound distribution . In one embodiment , the acous

Another embodiment provides a method for producing a tic filter comprises an acoustic resonator filled with sound phase plug for an omnidirectional loudspeaker . The method 45 absorbing material ( i . e . , acoustic damping material ) . The comprises identifying resonances in a cavity of the omnidi - acoustic filter may be used to attenuate peaks and dips in rectional loudspeaker to remove and fabricate a phase plug f requency response curves for the loudspeaker at a specific for removing acoustic amplification generated by the reso - frequency . The acoustic filter may also be used to attenuate nances . The phase plug comprises an acoustic resonator resonances . For example , the acoustic filter may reduce including acoustic damping material . 50 distortion amplification and damp resonances in the cavity One embodiment provides a method for removing acous - 109 . The acoustic filter is positioned directly across one or

tic amplification in a cavity between a diaphragm and a more distortion inducing elements of the loudspeaker . phase plug of an omnidirectional loudspeaker . The method One embodiment provides a physical acoustic filter that comprises generating , utilizing a sound source of the omni - may be integrated into a phase plug of a loudspeaker to directional loudspeaker , sound and removing acoustic 55 attenuate one or more peaks in omnidirectional sound dis amplification generated by resonances in the cavity by tribution . Acoustic damping characteristics of the sound attenuating , utilizing an acoustic resonator of the phase plug , absorbing material tunes a Q - factor of attenuation to a the sound at a pre - selected frequency . The acoustic resonator Q - factor of resonance to reduce dips in the sound distribu comprises an acoustic damping material . tion and dips in frequency response curves caused by

FIG . 1 illustrates an exemplary cross - section of an omni - 60 resonances in the cavity 109 . The acoustic filter allows a directional loudspeaker 100 . The loudspeaker 100 is rota - sound source of the loudspeaker to be used at a wider band tionally symmetric about an axis of symmetry 104 . The of frequencies ; otherwise , dips in frequency response curves loudspeaker 100 comprises a first axisymmetric loudspeaker around the resonances may severely limit bandwidth at enclosure 102 ( “ first enclosure ” ) , a second axisymmetric which the loudspeaker can produce significant sound levels . loudspeaker enclosure 118 ( " second enclosure ” ) , and a 65 Dips in frequency response curves are more difficult to phase plug 105 . The phase plug 105 is positioned at a bottom equalize at a level of an input signal because additional section 100A of the loudspeaker 100 . The second enclosure energy is required to enhance the input signal . The acoustic

US 10 , 034 , 081 B2

filter reduces some of the acoustic phenomena that create reduced for a loudspeaker 100 with a physical acoustic filter . dips in frequency response curves , thereby eliminating bur - Therefore , a physical acoustic filter provided by the modi den on an equalizer and enhancing sound quality . fied phase plug 155 reduces magnitude of peaks and dips in FIGS . 2 - 3 each illustrate a cross - section of an example a frequency response curve for a loudspeaker 100 , thereby

modified phase plug 155 for an omnidirectional loudspeaker 5 enhancing sound quality of the loudspeaker 100 . 100 , in accordance with an embodiment . The modified phase Further , as demonstrated by the second and third fre plug 155 comprises a base 155B including an acoustic quency response curves 192 and 193 , the amount of acoustic resonator 159 filled with acoustic damping material 158 . The damping material included in a physical acoustic filter also resonator 159 and the acoustic damping material 158 com - influences frequency response . bined provide a physical acoustic filter . 10 In this specification , the term " absorber ” generally

In this specification , a , denotes an amount ( i . e . , quantity ) denotes an acoustic resonator filled with acoustic damping of the acoustic damping material 158 used to fill the reso - material ( i . e . , sound absorbing material ) . nator 159 , t , denotes a type of the acoustic damping material FIG . 5A illustrates a cross - section of another example 158 , w , denotes a first dimension ( e . g . , diameter ) of the modified phase plug 200 for an omnidirectional loudspeaker resonator 159 , and h , denotes a second dimension ( e . g . , 15 100 , wherein the modified phase plug 200 includes a flat height / depth ) of the resonator 159 . The dimensions w , and shaped absorber without a perforated plate , in accordance h , of the resonator 159 and the amount a , of the acoustic with an embodiment . The modified phase plug 200 com damping material 158 are not limited to any specific range . prises a base 200B including an acoustic resonator 209 filled

Examples of types of acoustic damping material 158 may with acoustic damping material 208 . The resonator 209 and include , but are not limited to , fiberglass , Dacron , rockwool , 20 the acoustic damping material 208 combined provide a glasswool , foam ( e . g . , polyethylene foam ) , and mineral physical acoustic filter . The resonator 209 has a flat upper wool . The resonator 159 may comprise only one type of surface ( i . e . , flat top ) 200T . The acoustic damping material acoustic damping material 158 or a combination of different 208 is exposed to air in the cavity 109 . In one embodiment , types of acoustic damping material 158 . For example , in one a retaining structure ( e . g . , a wire mesh ) may be used to embodiment , fiberglass is used to fully fill the resonator 159 . 25 maintain the acoustic damping material 208 in place and

The resonator 159 is shaped / dimensioned such that the prevent the acoustic damping material 208 from falling out resonator 159 can be precisely tuned to attenuate sound at of the resonator 209 . The retaining structure does not affect selected frequencies . Further , “ sharpness ” of attenuation is the acoustics of the loudspeaker ( e . g . , does not affect acous based on acoustic damping characteristics of the acoustic tic damping ) . damping material 158 . For example , if the acoustic damping 30 FIG . 5B illustrates a cross - section of another example material 158 has a small amount of acoustic damping , the modified phase plug 210 for an omnidirectional loudspeaker resonator 159 is effective at attenuating a narrow band of 100 , wherein the modified phase plug 210 includes a flat frequencies ( i . e . , a high Q - factor of attenuation ) . As another shaped absorber with a perforated plate , in accordance with example , if the acoustic damping material 158 has a higher an embodiment . The modified phase plug 210 comprises a amount of acoustic damping , the resonator 159 provides 35 base 210B including an acoustic resonator 219 filled with increased bandwidth at which sound is attenuated but acoustic damping material 218 . The resonator 219 and the decreased effectiveness ( i . e . , a low Q - factor of attenuation ) . acoustic damping material 218 combined provide a physical

To manufacture the modified phase plug 155 , a shape of acoustic filter . The resonator 219 has a flat upper surface the resonator 159 , dimensions w , and h , of the resonator 210T . 159 , type t , of acoustic damping material 158 to use , and 40 A perforated plate 211 is attached to ( partially ) cover the amount a , of the acoustic damping material 158 to fill the flat upper surface 210T to increase effective acoustic damp resonator 159 with are determined based on an application ing and maintain the acoustic damping material 218 in place . and / or size of the loudspeaker 100 . The perforated plate 211 improves performance of the

In one example embodiment , a cross - section of the reso acoustic filter and acts as a barrier for the acoustic damping nator 159 has , but is not limited to , one of the following 45 material 218 , preventing the acoustic damping material 218 three - dimensional ( 3D ) shapes : a sphere ( see FIG . 7B as an from falling out of the resonator 219 . A shape of the example ) , a rectangular prism ( see FIG . 7D as an example ) , perforated plate 211 may be based on a diameter W4 of the a cylinder ( see FIG . 7A as an example ) , an undefined shape resonator 219 and a thickness of the perforated plate 211 . ( see FIG . 7E as an example ) , etc . The perforated plate 211 may include one or more openings /

In one example implementation , the resonator 159 is a 50 holes spaced regularly or irregularly across the perforated cylinder with a height / depth of 28 mm and a diameter of 21 plate 211 . The openings / holes allow soundwaves to propa mm . gate into the resonator 219 . An open - ratio of the perforated

FIG . 4 is an example graph 190 illustrating multiple plate 211 ( i . e . , a ratio indicating how much of the perforated frequency response curves , in accordance with one embodi plate 211 includes openings / holes ) and a diameter of each ment . Specifically , the graph 190 shows a first frequency 55 opening / hole may be based on application and / or size of the response curve 191 for a loudspeaker 100 without a physical loudspeaker 100 . In one embodiment , the diameter of each acoustic filter , a second frequency response curve 192 for a opening / hole may be less than 2 mm and the open - ratio of loudspeaker 100 with a physical acoustic filter comprising the perforated plate 211 may be less than 0 . 6 . acoustic damping material ( e . g . , fiberglass ) of density 27 . 48 FIG . 5C illustrates a cross - section of another example kg / m ” , and a third frequency response curve 193 for a 60 modified phase plug 220 for an omnidirectional loudspeaker loudspeaker 100 with a physical acoustic filter comprising 100 , wherein the modified phase plug 220 includes a curved acoustic damping material ( e . g . , fiberglass ) of density 18 . 32 shaped absorber without a perforated plate , in accordance kg / m " . The first frequency response curve 191 includes a with an embodiment . The modified phase plug 220 com peak A , around 1500 Hz and a dip B , around 4000 Hz . By prises a base 220B including an acoustic resonator 229 filled comparison , as shown by the second and third frequency 65 with acoustic damping material 228 . The resonator 229 and response curves 192 and 193 , the peak A , around 1500 Hz the acoustic damping material 228 combined provide a is eliminated and the dip B , around 4000 Hz is greatly physical acoustic filter . The resonator 229 has a curved

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$ ) .

upper surface ( i . e . , curved top ) 220T . The acoustic damping rested on top of a flat surface 611 . The loudspeaker 100 material 228 is exposed to air in the cavity 109 . In one includes a modified phase plug 230 . embodiment , a retaining structure ( e . g . , a wire mesh ) may be One embodiment provides a protruding phase plug for an used to maintain the acoustic damping material 228 in place omnidirectional loudspeaker 100 . FIGS . 6A - 6B each illus and prevent the acoustic damping material 228 from falling 5 trate a cross - section of an example protruding phase plug out of the resonator 229 . The retaining structure does not 305 for an omnidirectional loudspeaker 100 , in accordance affect the acoustics of the loudspeaker ( e . g . , does not affect with an embodiment . The protruding phase plug 305 com acoustic damping ) . prises a base 305B and a protruding portion 305P extending

A dimension of the resonator 229 may vary over a range from a central area of the base 305B . The protruding portion The curved upper surface 220T increases a dimension ( e . g . , 10 305P extends into an interior cavity 102A ( FIG . 1 ) of a first height / depth ) of the resonator 229 . enclosure 102 of the loudspeaker 100 .

FIG . 5D illustrates a cross - section of another example Specifically , as shown in FIGS . 6A - 6B , the protruding modified phase plug 230 for an omnidirectional loudspeaker portion 305P extends past the diaphragm 106 ( in a rest 100 , wherein the modified phase plug 230 includes a curved position ) of the loudspeaker 100 , and into the region 106S shaped absorber with a perforated plate , in accordance with 15 ( FIG . 1 ) of space between the diaphragm 106 and the an embodiment . The modified phase plug 230 comprises a transducer 107 of the loudspeaker 100 . The diaphragm 106 base 230B including an acoustic resonator 239 filled with includes an opening 106H ( i . e . , a hole ) shaped for receiving acoustic damping material 238 . The resonator 239 and the the protruding portion 305P . The opening 106H is positioned acoustic damping material 238 combined provide a physical at a center of the diaphragm 106 . acoustic filter . The resonator 239 has a curved upper surface 20 The protruding phase plug 305 provides a physical acous 230T . tic filter comprising a resonator 309 filled with acoustic

A perforated plate 231 is attached to a portion of the damping material 308 . modified phase plug ( e . g . , the curved upper surface 230T ) to In this specification , a , denotes an amount ( i . e . , quantity ) increase effective acoustic damping and maintain the acous - of the acoustic damping material 308 used to fill the reso tic damping material 238 in place . The perforated plate 231 25 nator 309 , t , denotes a type of the acoustic damping material improves performance of the acoustic filter and acts as a 308 , W , denotes a first dimension ( e . g . , diameter ) of the barrier for the acoustic damping material 238 , preventing the resonator 309 , and h , denotes a second dimension ( e . g . , acoustic damping material 238 from falling out of the height ) of the resonator 309 . The dimensions w , and h , of resonator 239 . A shape of the perforated plate 231 may be the resonator 309 and the amount a , of the acoustic damping based on a diameter W , of the resonator 239 and a thickness 30 material 308 are not limited to any specific range . of the perforated plate 231 . The perforated plate 231 may Examples of types of acoustic damping material 308 may include one or more openings / holes spaced regularly or include , but are not limited to , fiberglass , Dacron , rockwool , irregularly across the perforated plate 231 . The openings g lasswool , foam ( e . g . , polyethylene foam ) , and mineral holes allow soundwaves to propagate into the resonator 239 . wool . The resonator 308 may comprise only one type of An open - ratio of the perforated plate 231 ( i . e . , a ratio 35 acoustic damping material 308 or a combination of different indicating how much of the perforated plate 231 includes types of acoustic damping material 308 . For example , in one openings / holes ) and a diameter of each opening / hole may be embodiment , fiberglass is used to fully fill the resonator 309 . based on application and / or size of the loudspeaker 100 . In To manufacture the protruding phase plug 305 , a shape of one embodiment , the diameter of each opening / hole may be the resonator 309 , dimensions w , and h , of the resonator less than 2 mm and the open - ratio of the perforated plate 231 40 309 , type t , of acoustic damping material 308 to use , and may be less than 0 . 6 . amount a , of the acoustic damping material 308 to fill the

FIG . 5E is another example graph 250 illustrating mul - resonator 309 with are determined based on an application tiple frequency response curves , in accordance with one and / or size of the loudspeaker 100 . embodiment . Specifically , the graph 250 shows a first fre - In one example embodiment , a cross - section of the reso quency response curve 251 for a loudspeaker 100 without a 45 nator 309 has , but is not limited to , one of the following physical acoustic filter , a second frequency response curve three - dimensional ( 3D ) shapes : a sphere ( see FIG . 7B as an 252 for a loudspeaker 100 with a curved shaped absorber example ) , a rectangular prism ( see FIG . 7D as an example ) , with a perforated plate , and a third frequency response curve a cylinder ( see FIG . 7A as an example ) , an undefined shape 253 for a loudspeaker 100 with a flat shaped absorber with ( see FIG . 7E as an example ) , etc . a perforated plate . As demonstrated by the second and third 50 In one example implementation , the resonator 309 is a frequency response curves 252 and 253 , modified phase rectangular prism with a height of 50 mm and a diameter of plugs 210 and 230 reduce magnitude of peaks and dips in a 15 mm . frequency response curve for a loudspeaker 100 , thereby FIG . 6C is another example graph 350 illustrating mul enhancing sound quality of the loudspeaker 100 . tiple frequency response curves , in accordance with one

FIG . 5F illustrates a top view of an example modified 55 embodiment . Specifically , the graph 350 shows a first fre phase plug 200 for an omnidirectional loudspeaker 100 , quency response curve 351 for a loudspeaker 100 without a wherein the modified phase plug 200 includes a curved physical acoustic filter , and a second frequency response shaped absorber with a perforated plate , in accordance with curve 352 for a loudspeaker 100 with a protruding phase an embodiment . plug 305 . The first frequency response curve 351 includes a

FIG . 5G illustrates a top view of an example modified 60 peak A , around 1500 Hz , a dip B , around 4000 Hz , and phase plug 210 for an omnidirectional loudspeaker 100 , additional dips C2 and D2 around 6000 Hz and 9000 Hz wherein the modified phase plug 210 includes a flat shaped respectively . By comparison , as shown by the second fre absorber with a perforated plate 211 , in accordance with an quency response curve 352 , the peak A , around 1500 Hz and embodiment . the dip B , around 4000 Hz are eliminated , and the additional

FIG . 5H illustrates sound pressure wave fronts 610 65 dips C2 and D , around 6000 Hz and 9000 Hz respectively are around an omnidirectional loudspeaker 100 in operation , in greatly reduced for a loudspeaker 100 with a protruding accordance with an embodiment . The loudspeaker 100 is phase plug 305 . Therefore , a protruding phase plug 305

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reduces magnitude of peaks and dips in a frequency the resonator 719 lies flush inside the modified phase plug response curve for a loudspeaker 100 , thereby enhancing 7 10 ( i . e . , does not extend / protrude into the cavity 109 ) . sound quality of the loudspeaker 100 . The resonator attenuates frequencies ( in units of Hz )

FIG . 6D illustrates a cross - section of the protruding phase around fresonance . In one embodiment , for a spherical shaped plug 305 with a perforated ring 410W , in accordance with an 5 resonator 719 , fresonance is represented in accordance with embodiment . To increase effective acoustic damping of the equation ( 3 ) provided below : resonator 309 , a single encircling perforated ring 410W may be attached to an exposed region 305E ( FIG . 6F ) of the fresonance = ( v / T ) * ( 3d / 6 . 8D3 ) 12 , ( 3 ) protruding portion 305P that is exposed to air .

FIG . 6E illustrates a cross - section of the protruding phase 10 10 wherein D denotes a diameter at a center of the resonator plug 305 with a perforated ring 410W and an extended 719 in units of meter , and d denotes a diameter at a top absorber 416 , in accordance with an embodiment . In one section 715 of the resonator 719 in units of meter . embodiment , the base 305B may be filled with additional FIG . 7C illustrates a cross - section of an example modified acoustic damping material to form an extended absorber phase plug 720 comprising a Helmholtz resonator , in accor 416 . The extended absorber 416 helps to attenuate peaks at 15 dance with an embodiment . As shown in FIG . 7C , the lower frequencies . Helmholtz resonator comprises a spherical resonator 728

FIG . 6F illustrates a cross - section of the protruding phase including a cylindrical neck 729 extending from a top of the plug 305 with an extended absorber 416 and without a spherical resonator 728 . The Helmholtz resonator lies flush perforated ring , in accordance with an embodiment . Some inside the modified phase plug 720 ( i . e . , does not extend / acoustic damping material inside the protruding portion 20 protrude into the cavity 109 ) . 305P is in direct contact with air surrounding an exposed In one embodiment , for a Helmholtz resonator , fresonance region 305E of the protruding portion 305P . is represented in accordance with equation ( 4 ) provided

FIG . 6G each illustrate a cross - section of an example below : protruding phase plug 505 for an omnidirectional loud speaker 100 , in accordance with an embodiment . The pro - 25 fresonance = ( v / ) * ( A / V Led ) 12 , ( 4 ) truding phase plug 505 comprises a base 505B and a protruding portion 505P extending from a central area of the wherein A denotes a cross - sectional area of the neck 729 , L base 305B . Unlike the protruding phase plug 305 . the denotes a length of the neck 729 , Vo denotes a volume of the protruding portion 505P extends only into the cavity 109 . resonator 728 , Lea is either L + 0 . 75d ( if the neck 729 is The protruding phase plug 505 provides a physical acoustic 30 unflanged , i . e . , the neck 729 protrudes into the cavity 109 ) filter comprising a resonator 509 filled with acoustic damp - or L + 0 . 85d ( if the neck 729 is flanged , i . e . , the neck 729 ends ing material 508 . The protruding phase plug 505 has a at a surface of the modified phase plug 720 ) , and d denotes curved upper surface 510T . a diameter of the neck 729 .

FIG . 6H illustrates a cross - section of the protruding phase FIG . 7D illustrates a cross - section of an example modified plug 505 with a perforated plate 510W , in accordance with 35 phase plug 730 comprising a rectangular prism shaped an embodiment . To increase effective acoustic damping of resonator 739 , in accordance with an embodiment . The the resonator 509 , a perforated ring 410W may be attached resonator 739 lies flush inside the modified phase plug 730 to a region of the protruding portion 505P that is exposed to ( i . e . , does not extend / protrude into the cavity 109 ) . air . FIG . 7E illustrates a cross - section of an example modified

FIG . 7A illustrates a cross - section of an example modified 40 phase plug 740 comprising an irregular shaped resonator phase plug 700 comprising a cylindrical shaped resonator 749 , in accordance with an embodiment . As shown in FIG . 709 , in accordance with an embodiment . As shown in FIG . 7E , a top section 749T , a middle section 749M , and a bottom 7A , the resonator 709 lies flush inside the modified phase section 749B of the resonator 749 have different shapes . The plug 700 ( i . e . , does not extend / protrude into the cavity 109 ) . resonator 749 lies flush inside the modified phase plug 740

In this specification , f is , denotes frequencies ( in units 45 ( i . e . , does not extend / protrude into the cavity 109 ) . of Hz ) amplified by a resonator , f . . . . . . . . denotes frequencies FIG . 8 is an example flowchart of a manufacturing ( in units of Hz ) attenuated by the resonator , n denotes an process 800 for producing a phase plug for an omnidirec integer number , and v denotes speed of sound in air in units tional loudspeaker , in accordance with an embodiment of the of meters / second . invention . In process block 801 , identify resonances in a

In one embodiment , for a cylindrical shaped resonator 50 cavity of the omnidirectional loudspeaker to remove . 709 , f . , is represented in accordance with equation ( 1 ) In process block 802 , determine at least one phase plug provided below : property suitable for removing acoustic amplification gen

erated by the resonances based on an application and a size Samplify = nv / [ 4 ( L + 0 . 4d , ( 1 ) of the omnidirectional loudspeaker .

55 In process block 803 , fabricate a phase plug for removing wherein L denotes a length of the resonator 709 in units of the acoustic amplification based on the at least one phase meter , d denotes a diameter of the resonator 709 in units of plug property , wherein the phase plug comprises an acoustic meter , and n is an odd integer number . resonator including acoustic damping material . In one embodiment , for a cylindrical shaped resonator In process block 804 , position a portion of the phase plug 709 , fattenuate is represented in accordance with equation ( 2 ) on ( 4 ) 60 directly across from a radiating surface of the omnidirec provided below : tional loudspeaker in the path of sound propagation . FIG . 9 is an example flowchart 900 for removing acoustic

fattenuate = nv / [ 4 ( L + 0 . 4d ) ] , amplification in a cavity between a diaphragm and a phase wherein n is an even integer number . plug of an omnidirectional loudspeaker , in accordance with

FIG . 7B illustrates a cross - section of an example modified 65 an embodiment of the invention . In process block 901 , phase plug 710 comprising a spherical shaped resonator 719 , generate , utilizing a sound source of the omnidirectional in accordance with an embodiment . As shown in FIG . 7B , loudspeaker , sound .

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fly ( 2 )

11

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In process block 902 , remove acoustic amplification gen fabricating a phase plug for removing acoustic amplifi erated by resonances in the cavity by attenuating , utilizing cation generated by the resonances , wherein the radi an acoustic resonator of the phase plug , the sound at a ating surface is positioned above and separate from the pre - selected frequency phase plug , the phase plug comprises a base including

Though the embodiments have been described with ref - 5 an acoustic resonator disposed within a portion of the erence to certain versions thereof ; however , other versions base , the acoustic resonator is at least partially filled are possible . Therefore , the spirit and scope of the appended with acoustic damping material , the acoustic resonator claims should not be limited to the description of the and the acoustic damping material combined attenuate preferred versions contained herein . sound at a frequency that is based at least in part on a What is claimed is : physical characteristic of the acoustic resonator , and a 1 . An omnidirectional loudspeaker , comprising : portion of the acoustic resonator including a portion of a phase plug comprising a base ; the acoustic damping material is positioned in a path of a radiating surface positioned above and separate from the

phase plug ; and sound propagation and protrudes into a cavity between an acoustic resonator disposed within a portion of the 15 the radiating surface and the phase plug .

base , wherein the acoustic resonator is at least partially 13 . The method of claim 12 , further comprising : filled with acoustic damping material , the acoustic determining at least one phase plug property suitable for resonator and the acoustic damping material combined removing the acoustic amplification based on an appli attenuate sound at a frequency that is based at least in cation and a size of the omnidirectional loudspeaker , part on a physical characteristic of the acoustic reso - 20 wherein the phase plug is fabricated based on the at nator , and a portion of the acoustic resonator including least one phase plug property , and the at least one phase a portion of the acoustic damping material is positioned plug property includes a physical characteristic of the in a path of sound propagation and protrudes into a acoustic resonator . cavity between the radiating surface and the phase 14 . The method of claim 13 , wherein the determining at plug . 25 least one phase plug property comprises :

2 . The omnidirectional loudspeaker of claim 1 , wherein determining a shape of the acoustic resonator ; the acoustic resonator is tuned to attenuate sound at a determining a dimension of the acoustic resonator ; pre - selected frequency . determining a type of the acoustic damping material ; and

3 . The omnidirectional loudspeaker of claim 1 , wherein determining an amount of the acoustic damping material the acoustic resonator removes acoustic amplification cre - 30 required to fill the acoustic resonator . ated by resonances in the cavity . 15 . The method of claim 12 , further comprising : 4 . The omnidirectional loudspeaker of claim 3 , wherein the acoustic damping material tunes a Q - factor of attenua positioning the portion of the acoustic resonator including tion to a Q - factor of the resonances in the cavity . the portion of the acoustic damping material directly

5 . The omnidirectional loudspeaker of claim 3 , wherein 35 across from the radiating surface in the path of sound the acoustic resonator has a curved upper surface . propagation .

6 . The omnidirectional loudspeaker of claim 5 , wherein a 16 . The method of claim 15 , wherein the portion of the perforated plate conforms to the curved upper surface . acoustic resonator including the portion of the acoustic

7 . The omnidirectional loudspeaker of claim 1 , wherein damping material extends into the cavity . the acoustic resonator has a flat upper surface . 40 17 . The method of claim 16 , further comprising :

8 . The omnidirectional loudspeaker of claim 7 , wherein a attaching perforated ring to a region of the portion of the perforated plate is on the flat upper surface . acoustic resonator including the portion of the acoustic

9 . The omnidirectional loudspeaker of claim 1 , further damping material exposed to air in the cavity . comprising : 18 . The method of claim 12 , further comprising :

an axisymmetric loudspeaker enclosure , wherein the radi - 45 tuning the acoustic resonator to attenuate sound generated ating surface is disposed inside the axisymmetric loud by a sound source of the omnidirectional loudspeaker at speaker enclosure ; and a pre - selected frequency .

a transducer disposed inside the axisymmetric loud 19 . A method for removing acoustic amplification in a speaker enclosure ; cavity between a diaphragm and a phase plug of an omni

wherein the portion of the acoustic resonator including the 50 directional loudspeaker , comprising : portion of the acoustic damping material extends generating , utilizing a sound source of the omnidirec through a recess of the radiating surface and into a tional loudspeaker , sound ; and region of space between the radiating surface and a removing acoustic amplification generated by resonances former of the transducer inside the axisymmetric loud in the cavity utilizing the phase plug , wherein the speaker enclosure . 55 10 . The omnidirectional loudspeaker of claim 9 , wherein diaphragm is positioned above and separate from the

a perforated ring is attached to a region of the portion of the phase plug , the phase plug comprises a base including acoustic resonator including the portion of the acoustic an acoustic resonator disposed within a portion of the damping material exposed to air in the cavity . base , the acoustic resonator is at least partially filled

11 . The omnidirectional loudspeaker of claim 1 , wherein 60 with acoustic damping material , the acoustic resonator a remaining portion of the base of the phase plug comprises and the acoustic damping material combined attenuate additional acoustic damping material . the sound at a frequency that is based at least in part on

12 . A method for producing a phase plug for an omnidi a physical characteristic of the acoustic resonator , and rectional loudspeaker including a radiating surface , com a portion of the acoustic resonator including a portion prising : of the acoustic damping material is positioned in a path

identifying resonances in a cavity of the omnidirectional of sound propagation and protrudes into a cavity loudspeaker to remove ; and between the diaphragm and the phase plug .

US 10 , 034 , 081 B2 13 14

20 . The method of claim 19 , wherein the acoustic damp ing material tunes a Q - factor of attenuation to a Q - factor of the resonances in the cavity .

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THU NAMA UTAN ATAU TAMA NA UITATE

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