mfcc_3.m

实现用MFCC作为特证向量的孤立词识别系统

function out=MFCC_3(in,cofnumber,fs)
%这个函数是用来计算摩尔倒谱系数
%输入为预处理后的矩阵 摩尔滤波器个数 还有采样频率
%输出就是输入矩阵的摩尔倒谱系数
in=abs(fft(in)).^2;
[a,b]=size(in);
in=in(1:a/2,:);
inter=fs/a;
index=ones(1,cofnumber);
Mef=2595*log10(1+fs/1400);
step_f=Mef/cofnumber;
for i=1:cofnumber
    k=i*step_f/2595;
    fre=(10.^(k)-1)*700;
    index(i)=floor(fre/inter);
end
template=zeros(a/2,cofnumber-2);
for i=1:cofnumber-2
    mid=index(i+1);
    step1=1/(mid-index(i));
    step2=1/(mid-index(i+2));
    for j=index(i):mid
        template(j,i)=(j-index(i))*step1;
    end
    for j=mid:index(i+2)
        template(j,i)=(j-index(i+2))*step2;
    end
end
out=zeros(cofnumber-2,b);
for i=1:b
    for j=1:cofnumber-2
        out(j,i)=sum(in(:,i).*template(:,j));
        k=out(j,i);
        if isnan(k)
            out(j,i) = 0;
        end
    end
end
out=dct(out);    
t=1:size(out,1);
A=2.5*sin(t*pi*1/(2*size(out,1)));
for i=1:size(out,2)
    out(:,i)=out(:,i).*A';
end