Subadaptive piecewise linear quantization for speech signal (64 kbit/s) compression

We propose a simple speech compression algorithm using subband division and subadaptive piecewise linear quantization for a voice-mail system. Voice mail is an audio equivalent of sending letters. The main differences are that computer networks deliver the mail and that electronic recording is used instead of letters. Although speech data are stored in a semiconductor memory device, its capacity and the available network capacity are limited. Therefore, it is necessary to compress the data as much as possible. However, there are two conditions to be satisfied. The first is that the reconstructed datum must be understood correctly. Second, we need to identify the sender. Signals with a rate of 64 kbit/s are compressed at a ratio of about 1/9 using the proposed subband division and subadaptive piecewise linear quantization.