A new compression technique of speech waveform
Makoto Morito, K. Hosoda, Koichiro Yamada · The Journal of the Acoustical Society of America · 1981
A new compression technique of speech waveform has been developed to synthesize natural speech at lower bit rates by a simple method. The basic process of this technique was constructed with waveform symmetrization, ADPCM coding and decoding, segment repetition, and amplitude interpolation. With this technique, it is possible to compress speech information at bit rates 2.8 to 6.5 kbite/s. In the analysis, 256 points of digital speech data were converted to a symmetric waveform having the same amplitude characteristics. The segment waveform (one pitch period length if voiced, 32 sampling periods length if unvoiced) was determined by the converted symmetric waveform and was coded using ADPCM. Further, in order to attain highly information compression, we defined the characteristic value giving periodicity of speech waveforms. In synthesis, one segment of the speech waveform was reproduced using ADPCM data. The same process was repeated several times according to the characteristic value determined in the analysis. This repetition is very efficient for the compression technique of speech waveform. Amplitude interpolation of segments was introduced to mitigate discontinuity between neighboring segments and was achieved by shifting the initial position of the pointer in the ADPCM decoding.