FREQUENCY DOMAIN SPEECH CODING

摘要

A sub-band coder for speech signals has a filter for dividing the frequency spectrum of speech signals input thereto into a plurality of sub-bands, from each of which is generated a respective series of samples of the filtered signal corresponding to that band. An encoder digitally encodes each series. A bit allocation unit varies the number of bits used for encoding the respective series in dependence on the relative energy contents of the sub-bands and is operative in accordance with a fixed set of n numbers, where n is the number of sub-bands, to allocate to the sub-band having the largest energy content the number of bits indicated by the largest number of the set and to allocate to successively lower energy bands successively smaller numbers from the set.