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Inverse filtering for virtual acoustic imaging systems

Inverse filtering for virtual acoustic imaging systems
Inverse filtering for virtual acoustic imaging systems
The research topic of this thesis is the use of inverse filtering for the design and
implementation of two-channel virtual acoustic imaging systems that utilise
loudspeakers. The basic objective of such systems is to invert the electroacoustic plant
between the input to the loudspeakers and the output at the listener’s ears and hence
make it possible for a pair of binaural signals to be locally reproduced at the position
of the listener’s ears. As a starting point for the research presented, a previously
introduced type of inverse filtering design is considered in which the inverse is
implemented with FIR filters. The basic formulation of this design is described and a
number of innovative points regarding its implementation are made. An experimental
procedure is then formulated for the evaluation of the effectiveness of this inverse
filtering design that is based on objective measurements of the inversion process.
Unlike previously employed methods that are based on computer simulations or
subjective experiments, the introduced experimental procedure is shown to be very
efficient in isolating and exactly quantifying the effect on the accuracy of the
inversion of a number of errors and approximations typically present in the
implementation. A detailed evaluation is thus presented of the inverse filtering design
at hand in realistic conditions of implementation. Subsequently, a novel method for
the off-line implementation of the inverse filtering is presented that utilises recursive
filters of lower order. In this method, the responses of the inverse filters are
decomposed into two parts, one realisable in forward time and one in backward time.
The effectiveness of this new method for the implementation of the inverse is tested
and compared with a small selection of the objective evaluation results described
above. Finally, an algorithm for the on-line implementation of the forward-backward
inverse filtering is proposed and its computational cost is compared with the currently
available frequency-domain block-processing filtering algorithms.
Papadopoulos, Timoleon
d1af8c5a-f58c-44c8-a4bb-6d2ad9695f95
Papadopoulos, Timoleon
d1af8c5a-f58c-44c8-a4bb-6d2ad9695f95
Nelson, Philip
5c6f5cc9-ea52-4fe2-9edf-05d696b0c1a9

Papadopoulos, Timoleon (2006) Inverse filtering for virtual acoustic imaging systems. University of Southampton, Institute of Sound and Vibration Research, Doctoral Thesis, 258pp.

Record type: Thesis (Doctoral)

Abstract

The research topic of this thesis is the use of inverse filtering for the design and
implementation of two-channel virtual acoustic imaging systems that utilise
loudspeakers. The basic objective of such systems is to invert the electroacoustic plant
between the input to the loudspeakers and the output at the listener’s ears and hence
make it possible for a pair of binaural signals to be locally reproduced at the position
of the listener’s ears. As a starting point for the research presented, a previously
introduced type of inverse filtering design is considered in which the inverse is
implemented with FIR filters. The basic formulation of this design is described and a
number of innovative points regarding its implementation are made. An experimental
procedure is then formulated for the evaluation of the effectiveness of this inverse
filtering design that is based on objective measurements of the inversion process.
Unlike previously employed methods that are based on computer simulations or
subjective experiments, the introduced experimental procedure is shown to be very
efficient in isolating and exactly quantifying the effect on the accuracy of the
inversion of a number of errors and approximations typically present in the
implementation. A detailed evaluation is thus presented of the inverse filtering design
at hand in realistic conditions of implementation. Subsequently, a novel method for
the off-line implementation of the inverse filtering is presented that utilises recursive
filters of lower order. In this method, the responses of the inverse filters are
decomposed into two parts, one realisable in forward time and one in backward time.
The effectiveness of this new method for the implementation of the inverse is tested
and compared with a small selection of the objective evaluation results described
above. Finally, an algorithm for the on-line implementation of the forward-backward
inverse filtering is proposed and its computational cost is compared with the currently
available frequency-domain block-processing filtering algorithms.

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Published date: May 2006
Organisations: University of Southampton

Identifiers

Local EPrints ID: 157421
URI: https://eprints.soton.ac.uk/id/eprint/157421
PURE UUID: 68cd54e2-99cb-4d16-ab42-e0ba1a5fbcb0

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Date deposited: 07 Jun 2010 13:59
Last modified: 18 Jul 2017 12:40

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Contributors

Author: Timoleon Papadopoulos
Thesis advisor: Philip Nelson

University divisions

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