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Details of Grant 

EPSRC Reference: EP/D04264X/1
Title: Precision Measurement and Correction of Microphone non-linear distortion
Principal Investigator: Chambers, Professor J
Other Investigators:
Researcher Co-Investigators:
Project Partners:
QinetiQ
Department: Sch of Engineering
Organisation: Cardiff University
Scheme: Standard Research (Pre-FEC)
Starts: 01 November 2005 Ends: 31 October 2006 Value (£): 62,295
EPSRC Research Topic Classifications:
Digital Signal Processing
EPSRC Industrial Sector Classifications:
Communications
Related Grants:
Panel History:  
Summary on Grant Application Form
The objective is to advance the state of the art in audio metrology and thereby ultimately provide progress towards unlimited precision in the measurement of audio signals through the application of adaptive correction techniques to mitigate non-linear distortion. The focus of the work is an initial experimental investigation of the problems of using a new multi-source non-linear distortion acoustic measurement technique. The fundamental novelty in this work is a recently proposed, but untested, novel technique for measuring the performance of a microphone by combining multi-frequency test signals in the acoustic domain. Exploitation of such a measurement technique is targeted at removing the present limit to the measurement of acoustic non-linearity posed by the threshold of total harmonic distortion (THD) available from metrology-class acoustic sine-wave generators. To complement the development of the correction algorithm within the proposal, the work packages have been carefully designed to progress the degree of precision of mathematical and electro-dynamic modelling of microphone non-linearity, i.e. experimental measurements are made in stages to move closer towards a model that accounts for practical distortion mechanisms revealed by the increased precision of the new measurement method. This provides a clear developmental thread through the work packages. In work package 1 we undertake experimental measurements and produce a database of audio recordings suitable for the evaluation of the double comb filter method for measurement of microphone non-linearity. In 2 we focus on improving microphone electro acoustic models. Workpage 3 uses these models to develop suitable alogorithms for adaptive correction of non-linearity. In workpackage 4 we study the suitability of the measurement method in the adaptive non-linearity correction of microphones in terms of ultimate THD and intermodulation distortion, to identify areas of new work.
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