Personal audio in a headrest
Personal audio in a headrest
Initial monopole simulations suggest that a single secondary source placed close to the primary source in the bright zone headrest performs significantly better than using two secondary sources located in the dark zone headrest. It is also shown that for a single dark zone located to the side of the bright zone, direct cancellation of the pressure at a microphone corresponding to the ear position closest to the bright zone gives very similar performance to directly maximising the contrast.
Using the source arrangement suggested from these simulations, a real-time implementation of the personal audio system has been developed and with which good performance has been achieved. The system achieves approximately 35dB of combined passive and active contrast up to 1kHz, with an upper frequency limit of around 2kHz. Subjective experiments show up to 7dB overall reduction in the levels are perceived in the dark zone when the system is active.
A BEM model of the full seat has also been developed, which is reasonably accurate at predicting the performance limits of the practical system, including the effects of reflection and adsorption of the seat and head.
Monopole and BEM models are then used to investigate suitable source arrangements and control strategies for two alternative geometries, where firstly multiple dark zones are considered, and then the problem of maintaining privacy while using a mobile phone with the speakerphone is considered as an alternative application. Good performance is obtained when there is a dark zone located in front as well as to the side, where measurements serve to verify the BEM predictions, and it is shown that the source pair should be rotated to point between the two dark zones for optimal performance. For the mobile phone application, it is shown that contrast maximum approaches the sound power minimization solution when the dark zone surrounds the sources.
University of Southampton
Jones, Matthew
7aaa98e2-a8e3-4eaf-9034-669c48cb893f
2007
Jones, Matthew
7aaa98e2-a8e3-4eaf-9034-669c48cb893f
Jones, Matthew
(2007)
Personal audio in a headrest.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Initial monopole simulations suggest that a single secondary source placed close to the primary source in the bright zone headrest performs significantly better than using two secondary sources located in the dark zone headrest. It is also shown that for a single dark zone located to the side of the bright zone, direct cancellation of the pressure at a microphone corresponding to the ear position closest to the bright zone gives very similar performance to directly maximising the contrast.
Using the source arrangement suggested from these simulations, a real-time implementation of the personal audio system has been developed and with which good performance has been achieved. The system achieves approximately 35dB of combined passive and active contrast up to 1kHz, with an upper frequency limit of around 2kHz. Subjective experiments show up to 7dB overall reduction in the levels are perceived in the dark zone when the system is active.
A BEM model of the full seat has also been developed, which is reasonably accurate at predicting the performance limits of the practical system, including the effects of reflection and adsorption of the seat and head.
Monopole and BEM models are then used to investigate suitable source arrangements and control strategies for two alternative geometries, where firstly multiple dark zones are considered, and then the problem of maintaining privacy while using a mobile phone with the speakerphone is considered as an alternative application. Good performance is obtained when there is a dark zone located in front as well as to the side, where measurements serve to verify the BEM predictions, and it is shown that the source pair should be rotated to point between the two dark zones for optimal performance. For the mobile phone application, it is shown that contrast maximum approaches the sound power minimization solution when the dark zone surrounds the sources.
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Published date: 2007
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Local EPrints ID: 466405
URI: http://eprints.soton.ac.uk/id/eprint/466405
PURE UUID: ddf2ffeb-aa0b-4c6d-8c4e-05869acf7fb6
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Date deposited: 05 Jul 2022 05:14
Last modified: 16 Mar 2024 20:41
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Author:
Matthew Jones
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