• noise suppression;
  • speech emphasis;
  • spectral subtraction;
  • 3GPP;
  • AMR


This paper discusses a noise suppressor for use in the standard AMR (adaptive multi-rate) voice codec in 3GPP (3rd Generation Partnership Project). The performance standards (TS 26.077) for 3GPP noise suppressors require both high quality and high noise suppression performance with limited computational complexity. This paper is based on the spectral subtraction method, and discusses the configuration in which spectral subtraction and amplitude suppression are mutually controlled according to the state of the input signal. The improved estimation of the subband S/N (signal-to-noise ratio) for use in the control of spectral subtraction and amplitude suppression is also discussed. The proposed method is evaluated through simulation experiments, and its effectiveness is verified. Subjective evaluation tests (evaluation by third parties) and objective evaluation tests were performed in accordance with 3GPP TS 26.077, and all 3GPP performance requirement standards were met. The system obtained the first performance endorsement from 3GPP in March 2002. © 2007 Wiley Periodicals, Inc. Syst Comp Jpn, 38(14): 90–102, 2007; Published online in Wiley InterScience ( DOI 10.1002/scj.20212