4 Description of Noise Suppression applied to AMR

06.773GPPMinimum Performance Requirements for Noise Suppresser Application to the AMR Speech EncoderTS

Noise Suppression for the AMR codec is a feature designed to enhance speech quality in a range of environments where there is significant (acoustic) background noise. The noise suppression function is a pre-processing module that is used to improve the signal to noise ratio of a speech signal prior to voice coding. In so doing it may use functions and/or data from the AMR speech encoding function. This specification defines recommended minimum performance requirements for such a function when it is implemented in the mobile station (operating on the uplink speech signal).

The AMR Speech decoder should not be altered by the Noise Suppression function.

It shall be possible to disable the operation of the noise suppression algorithm using signalling when commanded by the network.

4.1 Applicability of Noise Suppression to Basic Services.

This feature shall be applicable (as an option) to all speech calls where the narrowband AMR codec is utilised. Provision of the feature in AMR-capable mobile stations is a manufacturer dependent option. The network shall be able to enable or disable this noise suppression function both at call set-up and in call. Signalling between network and mobile to allow this control has been provided.