Comparison of 1-bit adaptive quantisers for speech coding

A 1-bit version of the recently proposed generalised hybrid adaptive quantiser (GHAQ) is compared with two other 1-bit adaptive quantisers, in terms of the signal-to-noise ratio obtained when coding speech in delta modulators. The GHAQ is found to have a clear advantage, particularly when the speech is acquired by a telephone microphone. It is also shown that the optimum coefficients of the predictor can be influenced substantially by the design of the adaptive quantiser, and a technique for finding suitable coefficients in this context is described.