{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/108006"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/108006","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Private audio delivery in reverberant spaces","abstract":"We study the problem of delivering private audio to multiple users in a reverberant room. New methods are proposed which work with specially designed noise signals and make constructive use of reverberation. First, traditional sound zones problem formulation is introduced. In this formulation, a loudspeaker array is used to create isolated soundfields as designated by the user. Traditional approaches such as acoustic contrast control (ACC) and pressure matching (PM) were devised as solutions to the sound zones problem, and they were proven to be effective. One aspect that has not been addressed by these methods is the privacy/security issue. With eavesdroppers present in the room, traditional approaches to sound zones problems do not ensure secure delivery of audio that prevents the eavesdroppers from comprehending the contents. Next, new methods are thus introduced which address the added privacy requirement. Instead of considering reverberation as unwelcome, the proposed formulation takes advantage of the multi-path nature and leverages the random-like echoes to simultaneously achieve sound focusing and eavesdropping prevention. Two methods are introduced. The first one is based on direct least-squares optimization; we refer to it as the Least-Squares (LS) method. The second one, adopted from the wireless communication literature, exploits the null space of the multiple-input-multiple-output channel matrix; we refer to it as the Null Space (NS) method. The two methods are evaluated and compared in numerical and real-world experiments. Both methods are shown to achieve sound focusing as well as very low signal-to-noise ratio (SNR) outside the focusing spots. The NS method provides sharper intelligibility drop which results in smaller, more spatially refined sound focusing spots. Subject to the usual limitations of sound zone methods such as long computation time or the requirement to know the impulse responses, both methods are proven to provide new solutions to sound zone problems with privacy constraints.","abstract_html":"We study the problem of delivering private audio to multiple users in a reverberant room. New methods are proposed which work with specially designed noise signals and make constructive use of reverberation. First, traditional sound zones problem formulation is introduced. In this formulation, a loudspeaker array is used to create isolated soundfields as designated by the user. Traditional approaches such as acoustic contrast control (ACC) and pressure matching (PM) were devised as solutions to the sound zones problem, and they were proven to be effective. One aspect that has not been addressed by these methods is the privacy/security issue. With eavesdroppers present in the room, traditional approaches to sound zones problems do not ensure secure delivery of audio that prevents the eavesdroppers from comprehending the contents. Next, new methods are thus introduced which address the added privacy requirement. Instead of considering reverberation as unwelcome, the proposed formulation takes advantage of the multi-path nature and leverages the random-like echoes to simultaneously achieve sound focusing and eavesdropping prevention. Two methods are introduced. The first one is based on direct least-squares optimization; we refer to it as the Least-Squares (LS) method. The second one, adopted from the wireless communication literature, exploits the null space of the multiple-input-multiple-output channel matrix; we refer to it as the Null Space (NS) method. The two methods are evaluated and compared in numerical and real-world experiments. Both methods are shown to achieve sound focusing as well as very low signal-to-noise ratio (SNR) outside the focusing spots. The NS method provides sharper intelligibility drop which results in smaller, more spatially refined sound focusing spots. Subject to the usual limitations of sound zone methods such as long computation time or the requirement to know the impulse responses, both methods are proven to provide new solutions to sound zone problems with privacy constraints.","abstract_has_math":false,"creators":["Liu, Yu-Jeh"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Electrical & Computer Engr","degree_department":null,"school":null,"contributors":["Dokmanic, Ivan"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2020,"date_issued":"2020-05","date_published":"2020-05","updated_at":"2026-07-22T22:24:47Z","subjects":["sound zone","reverberation","sound focusing","private audio","least-squares","null space","inverse problem","soundfield","room acoustics","eavesdropper","loudspeaker array"],"languages":["en"],"rights":["Copyright 2020 Yu-Jeh Liu"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/108006","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Dokmanic, Ivan"]},{"key":"dc:creator","label":"Author","values":["Liu, Yu-Jeh"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2020-05","2020-08-26T21:54:57Z","2020-05-11"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Electrical & Computer Engr"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["sound zone","reverberation","sound focusing","private audio","least-squares","null space","inverse problem","soundfield","room acoustics","eavesdropper","loudspeaker array"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2020 Yu-Jeh Liu"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/108006"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["We study the problem of delivering private audio to multiple users in a reverberant room. New methods are proposed which work with specially designed noise signals and make constructive use of reverberation. First, traditional sound zones problem formulation is introduced. In this formulation, a loudspeaker array is used to create isolated soundfields as designated by the user. Traditional approaches such as acoustic contrast control (ACC) and pressure matching (PM) were devised as solutions to the sound zones problem, and they were proven to be effective. One aspect that has not been addressed by these methods is the privacy/security issue. With eavesdroppers present in the room, traditional approaches to sound zones problems do not ensure secure delivery of audio that prevents the eavesdroppers from comprehending the contents. Next, new methods are thus introduced which address the added privacy requirement. Instead of considering reverberation as unwelcome, the proposed formulation takes advantage of the multi-path nature and leverages the random-like echoes to simultaneously achieve sound focusing and eavesdropping prevention. Two methods are introduced. The first one is based on direct least-squares optimization; we refer to it as the Least-Squares (LS) method. The second one, adopted from the wireless communication literature, exploits the null space of the multiple-input-multiple-output channel matrix; we refer to it as the Null Space (NS) method. The two methods are evaluated and compared in numerical and real-world experiments. Both methods are shown to achieve sound focusing as well as very low signal-to-noise ratio (SNR) outside the focusing spots. The NS method provides sharper intelligibility drop which results in smaller, more spatially refined sound focusing spots. Subject to the usual limitations of sound zone methods such as long computation time or the requirement to know the impulse responses, both methods are proven to provide new solutions to sound zone problems with privacy constraints.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2020-08-25 without embargo terms","The student, Yu-Jeh Liu, accepted the attached license on 2020-05-07 at 12:04.","The student, Yu-Jeh Liu, submitted this Thesis for approval on 2020-05-07 at 12:32.","This Thesis was approved for publication on 2020-05-11 at 10:35.","DSpace SAF Submission Ingestion Package generated from Vireo submission #15273 on 2020-08-25 at 17:12:41","Made available in DSpace on 2020-08-26T21:54:57Z (GMT). No. of bitstreams: 2 LIU-THESIS-2020.pdf: 90698096 bytes, checksum: 5d746b6777bd04bcd50ce3536b209a1e (MD5) LICENSE.txt: 4207 bytes, checksum: ecae43ec686c367460605b3a582b1875 (MD5) Previous issue date: 2020-05-11"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Private audio delivery in reverberant spaces"]}]}],"canonical_facts":{"dc:contributor":["Dokmanic, Ivan"],"dc:creator":["Liu, Yu-Jeh"],"dc:date":["2020-05","2020-08-26T21:54:57Z","2020-05-11"],"dc:description":["We study the problem of delivering private audio to multiple users in a reverberant room. New methods are proposed which work with specially designed noise signals and make constructive use of reverberation. First, traditional sound zones problem formulation is introduced. In this formulation, a loudspeaker array is used to create isolated soundfields as designated by the user. Traditional approaches such as acoustic contrast control (ACC) and pressure matching (PM) were devised as solutions to the sound zones problem, and they were proven to be effective. One aspect that has not been addressed by these methods is the privacy/security issue. With eavesdroppers present in the room, traditional approaches to sound zones problems do not ensure secure delivery of audio that prevents the eavesdroppers from comprehending the contents. Next, new methods are thus introduced which address the added privacy requirement. Instead of considering reverberation as unwelcome, the proposed formulation takes advantage of the multi-path nature and leverages the random-like echoes to simultaneously achieve sound focusing and eavesdropping prevention. Two methods are introduced. The first one is based on direct least-squares optimization; we refer to it as the Least-Squares (LS) method. The second one, adopted from the wireless communication literature, exploits the null space of the multiple-input-multiple-output channel matrix; we refer to it as the Null Space (NS) method. The two methods are evaluated and compared in numerical and real-world experiments. Both methods are shown to achieve sound focusing as well as very low signal-to-noise ratio (SNR) outside the focusing spots. The NS method provides sharper intelligibility drop which results in smaller, more spatially refined sound focusing spots. Subject to the usual limitations of sound zone methods such as long computation time or the requirement to know the impulse responses, both methods are proven to provide new solutions to sound zone problems with privacy constraints.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2020-08-25 without embargo terms","The student, Yu-Jeh Liu, accepted the attached license on 2020-05-07 at 12:04.","The student, Yu-Jeh Liu, submitted this Thesis for approval on 2020-05-07 at 12:32.","This Thesis was approved for publication on 2020-05-11 at 10:35.","DSpace SAF Submission Ingestion Package generated from Vireo submission #15273 on 2020-08-25 at 17:12:41","Made available in DSpace on 2020-08-26T21:54:57Z (GMT). No. of bitstreams: 2 LIU-THESIS-2020.pdf: 90698096 bytes, checksum: 5d746b6777bd04bcd50ce3536b209a1e (MD5) LICENSE.txt: 4207 bytes, checksum: ecae43ec686c367460605b3a582b1875 (MD5) Previous issue date: 2020-05-11"],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/108006"],"dc:language":["en"],"dc:rights":["Copyright 2020 Yu-Jeh Liu"],"dc:subject":["sound zone","reverberation","sound focusing","private audio","least-squares","null space","inverse problem","soundfield","room acoustics","eavesdropper","loudspeaker array"],"dc:title":["Private audio delivery in reverberant spaces"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Electrical & Computer Engr"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["M.S."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:47Z"}