Analysis, modeling and wide-area spatiotemporal control of low-frequency sound reproduction

4.00
Hdl Handle:
http://hdl.handle.net/10545/230034
Title:
Analysis, modeling and wide-area spatiotemporal control of low-frequency sound reproduction
Authors:
Hill, Adam J.
Abstract:
This research aims to develop a low-frequency response control methodology capable of delivering a consistent spectral and temporal response over a wide listening area. Low-frequency room acoustics are naturally plagued by room-modes, a result of standing waves at frequencies with wavelengths that are integer multiples of one or more room dimension. The standing wave pattern is different for each modal frequency, causing a complicated sound field exhibiting a highly position-dependent frequency response. Enhanced systems are investigated with multiple degrees of freedom (independently-controllable sound radiating sources) to provide adequate low-frequency response control. The proposed solution, termed a chameleon subwoofer array or CSA, adopts the most advantageous aspects of existing room-mode correction methodologies while emphasizing efficiency and practicality. Multiple degrees of freedom are ideally achieved by employing what is designated a hybrid subwoofer, which provides four orthogonal degrees of freedom configured within a modest-sized enclosure. The CSA software algorithm integrates both objective and subjective measures to address listener preferences including the possibility of individual real-time control. CSAs and existing techniques are evaluated within a novel acoustical modeling system (FDTD simulation toolbox) developed to meet the requirements of this research. Extensive virtual development of CSAs has led to experimentation using a prototype hybrid subwoofer. The resulting performance is in line with the simulations, whereby variance across a wide listening area is reduced by over 50% with only four degrees of freedom. A supplemental novel correction algorithm addresses correction issues at select narrow frequency bands. These frequencies are filtered from the signal and replaced using virtual bass to maintain all aural information, a psychoacoustical effect giving the impression of low-frequency. Virtual bass is synthesized using an original hybrid approach combining two mainstream synthesis procedures while suppressing each method‟s inherent weaknesses. This algorithm is demonstrated to improve CSA output efficiency while maintaining acceptable subjective performance.
Affiliation:
University of Essex
Citation:
Thesis (Ph.D.), School of Computer Science and Electronic Engineering -- University of Essex, 2012
Publisher:
University of Essex
Issue Date:
Jan-2012
URI:
http://hdl.handle.net/10545/230034
Additional Links:
http://serlib0.essex.ac.uk/search~S5?/dComputing+thesis/dcomputing+thesis/1%2C1%2C943%2CB/frameset&FF=dcomputing+thesis&4%2C%2C943/indexsort=r
Type:
Thesis
Language:
en_US
Appears in Collections:
Creative Technologies Research Group; Electrical, Electronic and Software Systems Research Group

Full metadata record

DC FieldValue Language
dc.contributor.authorHill, Adam J.en
dc.date.accessioned2012-06-21T10:58:39Z-
dc.date.available2012-06-21T10:58:39Z-
dc.date.issued2012-01-
dc.identifier.citationThesis (Ph.D.), School of Computer Science and Electronic Engineering -- University of Essex, 2012en
dc.identifier.urihttp://hdl.handle.net/10545/230034-
dc.description.abstractThis research aims to develop a low-frequency response control methodology capable of delivering a consistent spectral and temporal response over a wide listening area. Low-frequency room acoustics are naturally plagued by room-modes, a result of standing waves at frequencies with wavelengths that are integer multiples of one or more room dimension. The standing wave pattern is different for each modal frequency, causing a complicated sound field exhibiting a highly position-dependent frequency response. Enhanced systems are investigated with multiple degrees of freedom (independently-controllable sound radiating sources) to provide adequate low-frequency response control. The proposed solution, termed a chameleon subwoofer array or CSA, adopts the most advantageous aspects of existing room-mode correction methodologies while emphasizing efficiency and practicality. Multiple degrees of freedom are ideally achieved by employing what is designated a hybrid subwoofer, which provides four orthogonal degrees of freedom configured within a modest-sized enclosure. The CSA software algorithm integrates both objective and subjective measures to address listener preferences including the possibility of individual real-time control. CSAs and existing techniques are evaluated within a novel acoustical modeling system (FDTD simulation toolbox) developed to meet the requirements of this research. Extensive virtual development of CSAs has led to experimentation using a prototype hybrid subwoofer. The resulting performance is in line with the simulations, whereby variance across a wide listening area is reduced by over 50% with only four degrees of freedom. A supplemental novel correction algorithm addresses correction issues at select narrow frequency bands. These frequencies are filtered from the signal and replaced using virtual bass to maintain all aural information, a psychoacoustical effect giving the impression of low-frequency. Virtual bass is synthesized using an original hybrid approach combining two mainstream synthesis procedures while suppressing each method‟s inherent weaknesses. This algorithm is demonstrated to improve CSA output efficiency while maintaining acceptable subjective performance.en
dc.language.isoen_USen
dc.publisherUniversity of Essexen
dc.relation.urlhttp://serlib0.essex.ac.uk/search~S5?/dComputing+thesis/dcomputing+thesis/1%2C1%2C943%2CB/frameset&FF=dcomputing+thesis&4%2C%2C943/indexsort=ren
dc.subjectAcousticsen
dc.subjectDigital signal processingen
dc.subjectLoudspeakersen
dc.subjectAudio engineeringen
dc.subjectVirtual bassen
dc.subjectNonlinear processingen
dc.subjectFinite difference time domainen
dc.subjectLive sounden
dc.titleAnalysis, modeling and wide-area spatiotemporal control of low-frequency sound reproductionen
dc.typeThesisen
dc.contributor.departmentUniversity of Essexen
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