envextract.m

实现用MFCC作为特证向量的孤立词识别系统

function env=envextract(powerS,M,FS,bb)
%   ENVEXTRACT extracts the energy envolope of
%   sound power, powerS of size M, by the convolution with
%   a Hanning window of bb seconds.
%-------------------------------------------------
%   Ambo Liu    30 AUG 2002

HL=floor(bb*FS);
if (HL/2-floor(HL/2))==0,HL=HL+1;end; 
[a,b]=size(powerS);if b==1,powerS=powerS';end;

%---------------------------------------------
x=[fliplr(powerS(2:(HL+1)/2)),powerS,fliplr(powerS(M-(HL-1)/2:M-1))];
%   Data is extended by half of the length of smoothing window
%   at both ends of the data.  Modified on 10 Sept. 2002
%---------------------------------------------
hw=hann(HL);
env=conv(x,hw);
env=env(HL+1:M+HL);
%env=env/norm(env);