Dual-Mode Wideband Speech Compression

Many bandwidth extension techniques attempt to predict the high-band frequencies based on features extracted from the lower band. Recent work suggests that such methods are limiting because the correlation between the low band and the high band is insufficient for adequate representation. As a result, additional high-band information must be sent to the decoder. In this paper, we propose a dual mode wideband speech coding algorithm based on the principles of bandwidth extension. The principal contributions include a mode selection algorithm based on greedy algorithm that maximizes the loudness criteria, and a bandwidth extension algorithm based on a constrained MMSE estimator. Results reveal that the proposed system improves the quality of narrowband speech while performing at a lower bit rate.