Title :
Improvements of background sound coding in linear predictive speech coders
Author :
Wigren, Torbjorn ; Bergström, Anders ; Harrysson, Susanne ; Jansson, Fredrik ; Nilson, H.
Author_Institution :
Ericsson Radio Syst. AB, Stockholm, Sweden
Abstract :
A proper coding of background sounds has proven to be important in digital cellular telephone systems. It is therefore of considerable interest to find methods that improve also background sound coding, in particular in medium and low bitrate speech coders. In many coders operating around 8 kbps, one significant effect has been a swirling distortion when coding for example smooth car noise. The paper discusses the origin of this problem, and presents an algorithm that reduces swirling, giving a significant overall perceptual improvement, as shown by field tests in commercial D-AMPS systems in the US. A related new algorithm for error concealment is also presented. This method makes it possible to perceptually remove the effect of fading dips persisting for a few seconds, during nonspeech periods
Keywords :
audio coding; cellular radio; digital radio; fading; linear predictive coding; speech coding; vocoders; USA; background sound coding; commercial D-AMPS systems; digital cellular telephone systems; error concealment algorithm; fading dips; field tests; linear predictive speech coders; low bitrate speech coders; medium bitrate speech coders; nonspeech periods; smooth car noise; swirling distortion; Acoustic noise; Background noise; Band pass filters; Bit error rate; Bit rate; Fading; Signal to noise ratio; Speech codecs; Speech coding; Speech enhancement; System testing; Telephony;
Conference_Titel :
Acoustics, Speech, and Signal Processing, 1995. ICASSP-95., 1995 International Conference on
Conference_Location :
Detroit, MI
Print_ISBN :
0-7803-2431-5
DOI :
10.1109/ICASSP.1995.479513
