Noise Suppression Employing Short Delay Processing

Document type: Conference Papers
Peer reviewed: Yes
Author(s): Harald Gustafsson, Sven Nordholm, Ingvar Claesson
Title: Noise Suppression Employing Short Delay Processing
Conference name: Proceedings of the International Workshop on Intelligent Signal Processing and Communication Systems - ISPACS'99
Year: 1999
Pagination: 89-92
ISBN: 974-622-612-6
Publisher: King Mongkuts Inst. Technol
City: Phuket, Thailand
Organization: Blekinge Institute of Technology
Department: Department of Telecommunications and Signal Processing (Institutionen för telekommunikation och signalbehandling)
Department of Telecommunications and Signal Processing S-372 25 Ronneby
+46 455 38 50 00
Language: English
Abstract: Many telecommunication systems allow only a short delay in the terminal. This restriction stems from the fact that a delay will disturb the conversation. Therefore only a short delay is permissible in noise reduction processing. The well-known spectral subtraction method has been modified to introduce only a short delay and a variance reduced gain function. This modification is accomplished by viewing the spectral subtraction as an FFT filter design method which designs a time-varying filter for each block of data. The design will, however, only give the amplitude function, thus in order to obtain a causal filter a phase must be imposed. The spectral subtraction will not provide any phase information hence a minimum phase is imposed on the filter. The designed filter is transformed to the time-domain and the actual noise reduction filtering will be performed in the time-domain with only a short delay. The proposed method reduces the noise by 10 dB with a maximum processing delay of 7 samples.
Subject: Signal Processing\Speech Enhancement
Keywords: acoustic signal processing, delays, fast Fourier transforms, filtering theory, noise abatement, spectral analysis, time-domain analysis, time-varying filters