The present document specifies recommended minimum performance requirements for noise suppression algorithms intended for application in conjunction with the AMR speech encoder. This specification is for guidance purposes. Noise Suppression is intended to enhance the speech signal corrupted by acoustic noise at the input to the AMR speech encoder.
The use of this recommended minimum performance requirements specification is not mandatory except for those solutions intended to be endorsed by SMG11.
It is the intention of SMG11 to perform analysis and validation of any AMR noise suppression solution which is voluntarily brought to the attention of SMG11 in the future, using the requirements set out in this specification to facilitate such an analysis. In order for SMG11 to endorse such a solution, SMG11 must confirm that all the recommended minimum performance requirements are met.
The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific.
For a specific reference, subsequent revisions do not apply.
For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.
ITU-T Recommendation I.130 (1988): "General modelling methods - Method for the characterisation of telecommunications services supported by an ISDN and network capabilities of an ISDN".
GSM TR 01.04 (ETR 350): "Abbreviations and acronyms".
GSM TS 06.71: "Adaptive Multi-Rate (AMR); Speech processing functions; General description".
GSM TS 06.77: "Minimum Performance Requirements for Noise Suppresser Application to the AMR Speech Encoder".
GSM TS 06.73: "Adaptive Multi Rate (AMR) speech; ANSI-C code for the AMR speech codec".
GSM TS 03.50: "Transmission planning aspects of the speech service in the GSM Public Land Mobile Network (PLMN) system".
ITU-T Recommendation P.56: "Objective measurement of active speech level".
ITU-T Recommendation P.800: "Methods for subjective determination of transmission quality".
GSM TR 06.75: "Performance Characterization of the GSM Adaptive Multi-Rate (AMR) speech codec".
GSM TS 06.90: "Adaptive Multi-Rate (AMR) speech transcoding".
GSM TS 06.91: "Substitution and muting of lost frames for Adaptive Multi Rate (AMR) speech traffic channels".
GSM TS 06.92: "Comfort noise aspects for Adaptive Multi-Rate (AMR) speech traffic channels".
GSM TS 06.94: "Voice Activity Detection (VAD) for Adaptive Multi-Rate (AMR) speech traffic channels; General description".
GSM TR 01.04 
provides a list of abbreviations and acronyms used in GSM specifications. For the purposes of the present document, the following definitions and abbreviations also apply:
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.