In May 2008, Dr. Nikolay Gaubitch gave a talk at Microsoft Research (Redmond, Washington, USA). In this talk Dr. Gaubitch discusses a two-stage reverberation cancellation technique. First, the room transfer functions are identified. Second, a multichannel equalization method is presented in which the equalization is performed in the subband domain. You can find a more elaborate outline of his talk below. If you are interested you can watch the talk online.
Abstract
Identification and equalization of Room Transfer Functions (RTFs) is an important topic with several applications in acoustic signal processing. RTFs are often modelled as finite impulse response filters characterized by orders of thousands of taps and non-minimum phase. In practice, only approximate estimates of the actual RTFs are available due to measurement noise, limited estimation accuracy and temporal variation of source-receiver position. These issues make equalization a difficult problem. In the first part of this talk, I will present an adaptive method for blind system identification and introduce several constraints that can be used to improve the robustness of this method in noisy environments. Second, I will introduce a multichannel method for the equalization filter design utilizing decimated and oversampled subbands, where the fullband acoustic impulse response is decomposed into equivalent subband filters prior to equalization. This technique is more computationally efficient and more robust to RTF inaccuracies compared with the fullband counterpart.
Biography
Nikolay Gaubitch obtained the MEng degree in Computer Engineering from Queen Mary, University of London in 2002 and a PhD in Acoustic Signal Processing from Imperial College London in 2006. He has been a research associate with the Communications and Signal Processing Group at Imperial College London since 2005, first working on speech dereverberation for telecommunication applications and since December 2007 on a project dealing with speech cleaning and intelligibility enhancement. Nikolay's research interests include areas of microphone array processing, speech dereverberation, acoustic echo cancellation and speech enhancement.