Kolloquiumsvortrag: Prof. Dr. Patrick A. Naylor, Imperial College London, UK
Kiel, Kaiserstraße 2, Gebäude D, Aquarium
“Signal Processing Techniques for Acoustic Inference and Dereverberation”
The impact of acoustic propagation on speech signals observed at various points in space by microphones can be at the same time both degrading to the signals and useful for spatial awareness. The degradation is in the form of reverberation. This can have a negative effect on speech quality and can reduce the accuracy of automatic speech recognition. On the other hand, the spatial information observed along with the signal can be used to give spatial awareness of the source and microphone locations relative to the acoustic environment.
I find these contradictory effects intriguing. In this talk I shall discuss a single channel problem formulation for room geometry inference from the spatial information intrinsic in a room impulse response. Then I shall present some multichannel signal processing approaches to address the problem of reverberation in speech. In general, speech dereverberation can be achieved by first performing multichannel blind estimation of the acoustic propagation channels, and secondly applying a multichannel equalizer corresponding to the inverse of the acoustic system. This approach to dereverberation will be reviewed and some of the practical difficulties highlighted. Current and new approaches for the approximate inversion of the acoustic channel will be described.
Patrick Naylor received the BEng degree in Electronic and Electrical Engineering from the University of Sheffield, U.K., in 1986 and the PhD degree from Imperial College London, U.K., in 1990. Since 1990 he has been a member of academic staff in the Department of Electrical and Electronic Engineering at Imperial College London.
His research interests are in the areas of speech, audio and acoustic signal processing. He has worked in audio particular on adaptive signal processing and speech processing and has recently produced the first research textbook on dereverberation. Important topics in his work are microphone array signal processing, blind multichannel acoustic system identification and equalization, single and multi-channel speech enhancement and speech production modelling with particular focus on the analysis of the voice source signal. He is a director of the UK Centre for Law Enforcement Audio Research, a government funded centre tasked to undertake advanced research and to support the law enforcement agencies. In addition to his academic research, he enjoys several fruitful links with industry in the UK, USA.