Integrating Noise Suppression in Lpc-based Speech Codecs

Handset-free mobile speech communication in a noisy environment requires robust noise suppression with minimal speech degradation. Two solutions for the noise suppression problem are available: either the noise suppression module precedes the speech coder or noise suppression is integrated into the speech coder. Both solutions have been tested with signals picked up in a car under the same conditions, i.e. the same type of noise in a car with the same signal-to-noise ratio. Several simulation and listening tests have been performed and analyses in terms of segmental SNR as well as subjective measures are presented in this paper.