approx_map.m

来自「这个MATLAB程序是用于对音频信号进行降噪处理」· M 代码 · 共 26 行

function H = approx_map(gamma,xihat)
% APPROX_MAP - Approximate MAP spectral amplitude estimation (Wolfe and Godsill, 2001) 
%    H = APPROX_MAP(GAMMA,XIHAT) returns the approximate MAP spectral amplitude
%    estimation filter H given a posteriori signal-to-noise ratio (SNR) GAMMA
%    and an estimate XIHAT of a priori SNR.  GAMMA and XIHAT may be arrays but 
%    must be of equal dimension.
%
% References:
% 
% P. J. Wolfe and S. J. Godsill. Simple alternatives to the Ephraim and
% Malah suppression rule for speech enhancement. In Proc. IEEE Workshop on 
% Statistical Signal Processing, pages 496-499, August 2001.

% Author: Patrick J. Wolfe
%         Signal Processing Group
%         Cambridge University Engineering Department
%         [e-mail]
%
% Copyright (c) 2001 by Patrick J. Wolfe
% $Revision: 1.2 $  $Date: 2001/01/24 13:09:23 $

% Joint MAP spectral estimation filter calculation
%
upsilon = gamma.*xihat./(1+xihat);
H = (xihat+sqrt(xihat.^2+(1+xihat).*(xihat./gamma)))./(2.*(1+xihat));