ADAPTIVE METHOD AND APPARATUS FOR CODING SPEECH.

摘要

In a speech encoder, a Fourier transform (28) of the speech is provided. The Fourier transform is equalized (30) by normalizing the spectrum coefficients to a curve which approximates the shape of the spectrum. Both the curve and the equalized spectrum are encoded. In one system, scale factors (45) are generated and encoded for each of a plurality of subbands of a Fourier transform spectrum of speech. Based on those scale factors, the spectrum is equalized (46). Coefficients of a limited number of subbands (48) determined by the scale factors are encoded (50). The number of bits used to encode each coefficient of each transmitted subband is determined by the scale factor for each subband. At the receiver, coefficients of subbands which are not transmitted are approximated by means of a list replication technique (54).