Noise-adaptive perceptual weighting in the AMR-WB encoder for increased speech loudness in adverse far-end noise conditions
Abstract: In mobile communications, environmental noise often reduces the quality and intelligibility of speech. Problems caused by far-end noise, in the sending side of the communication channel, can be alleviated by using a noise reducing preprocessing stage before the encoder. In this study, a modification increasing the robustness of the encoder itself to background noise is proposed. Specifically, by using information already present in the encoder, the proposed method adjusts the perceptual weighting filter based on the characteristics of the noise to increase the prominence of the speech over the background noise. To evaluate the performance of the enhancement, the modification is implemented in the adaptive multi-rate wideband encoder and compared to the standard AMR-WB encoder in subjective tests. The results suggest that while the proposed modification increases the loudness of speech without affecting the quality significantly, for some female speakers the standard encoder is preferred over the enhancement.
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