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Some implications of causality in the active control of sound

Some implications of causality in the active control of sound
Some implications of causality in the active control of sound
Active noise control is evaluated for a variety of primary source waveforms in a one-dimensional free field, and white noise primary sources in a one-dimensional enclosure with varying end conditions. A study is made of the consequences of changes in cost function. Frequency and time domain methods of defining optimum causal controllers are reviewed, and the ability of an adaptive controller to approximate the optimum is evaluated. Time and frequency domain models of sound fields are compared, and good agreement shown, for both one-dimensional (duct) and three-dimensional (room) enclosed sound fields. The performance of finite causal secondary source controllers in reverberant rooms is observed for varying microphone locations and wall reflection coefficients. Multi-sensor, single-secondary active control systems for three-dimensional reverberant enclosures are briefly studied, for secondary sources near to and remote from the primary source. Constraints of causality, finite length, and calculation delay are imposed, with consequent effects on controller configuration and resulting sound field with primary and secondary sources in operation. Comparison is made between the sound field due to the primary source alone, the sound field due to primary and optimal secondary source, and the sound field due to primary and realizable secondary source.
Hough, Susan Patricia
0bd598d0-18ae-4b86-a2b6-02317f657843
Hough, Susan Patricia
0bd598d0-18ae-4b86-a2b6-02317f657843
Elliott, Stephen
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Hough, Susan Patricia (1988) Some implications of causality in the active control of sound. University of Southampton, Institute of Sound and Vibration Research, Doctoral Thesis, 171pp.

Record type: Thesis (Doctoral)

Abstract

Active noise control is evaluated for a variety of primary source waveforms in a one-dimensional free field, and white noise primary sources in a one-dimensional enclosure with varying end conditions. A study is made of the consequences of changes in cost function. Frequency and time domain methods of defining optimum causal controllers are reviewed, and the ability of an adaptive controller to approximate the optimum is evaluated. Time and frequency domain models of sound fields are compared, and good agreement shown, for both one-dimensional (duct) and three-dimensional (room) enclosed sound fields. The performance of finite causal secondary source controllers in reverberant rooms is observed for varying microphone locations and wall reflection coefficients. Multi-sensor, single-secondary active control systems for three-dimensional reverberant enclosures are briefly studied, for secondary sources near to and remote from the primary source. Constraints of causality, finite length, and calculation delay are imposed, with consequent effects on controller configuration and resulting sound field with primary and secondary sources in operation. Comparison is made between the sound field due to the primary source alone, the sound field due to primary and optimal secondary source, and the sound field due to primary and realizable secondary source.

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Published date: July 1988
Organisations: University of Southampton

Identifiers

Local EPrints ID: 52274
URI: https://eprints.soton.ac.uk/id/eprint/52274
PURE UUID: ebcd2443-1ff1-447f-b5ae-25aab33a89a2

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Date deposited: 26 Aug 2008
Last modified: 13 Mar 2019 20:44

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Contributors

Author: Susan Patricia Hough
Thesis advisor: Stephen Elliott

University divisions

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