10 Adaptive Multi-Rate Wideband speech codec comfort noise insertion

26.1713GPPAdaptive Multi-Rate - Wideband (AMR-WB) speech codecGeneral descriptionSpeech codec speech processing functionsTS

The adaptive multi-rate wideband comfort noise insertion function is described in [7].

When speech is absent, the synthesis in the speech decoder is different from the case when normal speech frames are received. The synthesis of an artificial noise based on the received non-speech parameters is termed comfort noise generation.

The comfort noise generation process is as follows:

– the evaluation of the acoustic background noise in the transmitter;

– the noise parameter encoding (SID frames) and decoding, and

– the generation of comfort noise in the receiver.

The comfort noise processes and the algorithm for updating the noise parameters during speech pauses are defined in detail in [7], and the corresponding C-code is defined in [3]. The comfort noise mechanism is based on the adaptive multi-rate wideband speech codec defined in [2].