An improved method of speech compression using warped LPC and MLT-SPIHT algorithm

Frequency -warped signal processing techniques are attractive to many wideband speech and audio applications since they have a clear connection to the frequency resolution of human hearing. A warped version of the linear predictive coding (LPC) for speech compression is implemented in this paper and an analysis of the application of Set Partitioning In Hierarchical Trees (SPIHT) algorithm to the compression of speech signals is performed. It has been shown that the proposed scheme i.e. Warped LPC with MLT_SPIHT algorithm produces an enhancement in speech quality. The proposed scheme is based on the combination of the Modulated Lapped Transform(MLT) and SPIHT. Comparisons are made with Plain LPC Coder, Voice Excited LPC Coder with the coding of the residual signal with DCT, Voice Excited LPC Coder with the coding of the residual signal with MLT and SPIHT. The performance of the coders described has been assessed by computer simulation in terms of a) Signal -to -noise ratio (SNR) b) Compression ratio c) Informal subjective listening test.