Title :
Enhancement of ADPCM speech coding with backward-adaptive algorithms for postfiltering and noise feedback
Author :
Ramamoorthy, V. ; Jayant, N.S. ; Cox, Richard V. ; Sondhi, Man Mohan
Author_Institution :
AT&T Bell Labs., Murray Hill, NJ, USA
fDate :
2/1/1988 12:00:00 AM
Abstract :
It is shown that postfiltering circuits based on higher order LPC (linear predictive coding) models can provide very low distortion in terms of special tilt. Thus, they can provide better speech enhancement than circuits based on the backward-adaptive pole-zero predictor in ADPCM (adaptive digital pulse code modulation). Quantitative criteria for designing postfiltering circuits based on higher-order LPC models are discussed. These postfilters are particularly attractive for systems where high-order LPC analysis is an integral part of the coding algorithm. In a subjective test that used a computer-simulated version of these circuits, enhanced ADPCM obtained a mean opinion score of 3.6 at 16 kb/s
Keywords :
digital filters; encoding; filtering and prediction theory; pulse-code modulation; speech analysis and processing; 16 kbits/s; ADPCM speech coding; adaptive digital pulse code modulation; backward-adaptive algorithms; coding algorithm; computer simulation; distortion; higher-order LPC models; linear predictive coding; noise feedback; postfiltering circuits; special tilt; speech enhancement; subjective test; Algorithm design and analysis; Circuit testing; Digital modulation; Linear predictive coding; Modulation coding; Predictive models; Pulse circuits; Pulse modulation; Speech coding; Speech enhancement;
Journal_Title :
Selected Areas in Communications, IEEE Journal on
