Delayless Subband Echo Cancellation

Document type: Conference Papers
Peer reviewed: Yes
Full text:
Author(s): Sven Nordholm, Jörgen Nordberg
Title: Delayless Subband Echo Cancellation
Conference name: Fifth International Congress on Sound and Vibration ICSV'5
Year: 1997
Pagination: 319-326
City: Adelaide
Organization: Blekinge Institute of Technology
Department: Dept. of Signal Processing (Institutionen för signalbehandling)
Dept. of Signal Processing S-372 25 Ronneby
+46 455 38 50 00
Authors e-mail: jno@bth.se
Language: English
Abstract: Echo suppression is a vital part of every communications system. The use of hands-free communication in cars, computer applications and video conferencing have created further demands for high-quality acoustic echo cancellation. In these applications the acoustic channel has, typically, a long impulse response in the order of 100 ms. Typical lengths of adaptive FIR-filters are 500-1500 taps, assuming a 12 kHz sampling frequency. In order to reduce the computational load and also to improve the convergence rate, sub-band processing schemes have been suggested.
This paper presents a study of a delayless sub-band adaptive filter. The study shows a possible echo suppression of about 30 dB and also an improved convergence rate when compared to a fullband LMS-filter. The main issues discussed are filter bank design and a simple speech detector that gives a drastic performance improvement.
Subject: Signal Processing\General
Keywords: Echo cancelation, Multi-rate
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