Method for speech coding under background noise conditions

摘要

A method of coding speech under background noise conditions wherein during active voice speech segments an analysis-by-synthesis method is used. However, when a background noise segment is detected, an adaptive code book (pitch prediction) contribution is used as a source of a pseudo-random sequence in order to provide a better representation of the background noise. An improved gain quantization scheme is also employed when a background noise segment is detected, wherein an energy of the total excitation with quantized gains is matched to an energy of total excitation with unquantized gains.