mfcc.m

基于DTW算法的孤立字识别系统。用Matlab编程实现语音信号的端点检测

function ccc=mfcc(x)
%归一化mel滤波器组系数
bank=melbankm(24,256,8000,0,0.5,'m');
bank=full(bank);
bank=bank/max(bank(:));

%dct系数，12*24
for k=1:12
    n=0:23;
    dctcoef(k,:)=cos((2*n+1)*k*pi/(2*24));
end

%归一化倒谱提升窗口
w=1+6*sin(pi*[1:12]./12);
w=w/max(w);

%预加重滤波器
xx=double(x);
xx=filter([1 -0.9375],1,xx);

%语音信号分帧
xx=enframe(xx,256,80);

%计算每帧的mfcc参数
for i=1:size(xx,1)
    y=xx(i,:);
    s=y'.*hamming(256);
    t=abs(fft(s));
    t=t.^2;
    c1=dctcoef*log(bank*t(1:129));
    c2=c1.*w';
    m(i,:)=c2';
end

%差分参数
dtm=zeros(size(m));
for i=3:size(m,1)-2
    dtm(i,:)=-2*m(i-2,:)-m(i-1,:)+m(i+1,:)+2*m(i+2,:);
end
dtm=dtm/3;

%合并mfcc参数和一阶差分mfcc参数
ccc=[m dtm];
%去处首位两帧，因为这两帧的一阶差分参数为0
ccc=ccc(3:size(m,1)-2,:);