edgedetect.m

MATLAB代码,利用语音信号的短时能量与短时过零率来达到自动检测语音的起止点。效果不错.

%语音信号的端点检测
[x,fs,nbits]=wavread('speech.wav');
x = x / max(abs(x));%幅度归一化到[-1,1]
%参数设置
FrameLen = 256;     %帧长
inc = 90;           %未重叠部分

amp1 = 10;          %短时能量阈值
amp2 = 2;      
zcr1 = 10;          %过零率阈值
zcr2 = 5;

minsilence = 6;  %用无声的长度来判断语音是否结束
minlen  = 15;    %判断是语音的最小长度
status  = 0;     %记录语音段的状态
count   = 0;     %语音序列的长度
silence = 0;     %无声的长度

%计算过零率
tmp1  = enframe(x(1:end-1), FrameLen,inc);
tmp2  = enframe(x(2:end)  , FrameLen,inc);
signs = (tmp1.*tmp2)<0;
diffs = (tmp1 -tmp2)>0.02;
zcr   = sum(signs.*diffs,2);

%计算短时能量
amp = sum((abs(enframe(filter([1 -0.9375], 1, x), FrameLen, inc))).^2, 2);

%调整能量门限
amp1 = min(amp1, max(amp)/4);
amp2 = min(amp2, max(amp)/8);

%开始端点检测
for n=1:length(zcr)
   goto = 0;
   switch status
   case {0,1}                   % 0 = 静音, 1 = 可能开始
      if amp(n) > amp1          % 确信进入语音段
         x1 = max(n-count-1,1); % 记录语音段的起始点
         status  = 2;
         silence = 0;
         count   = count + 1;
      elseif amp(n) > amp2 || zcr(n) > zcr2 % 可能处于语音段
         status = 1;
         count  = count + 1;
      else                       % 静音状态
         status  = 0;
         count   = 0;
      end
   case 2,                       % 2 = 语音段
      if amp(n) > amp2 ||zcr(n) > zcr2     % 保持在语音段
         
         count = count + 1;
      else                       % 语音将结束
         silence = silence+1;
         if silence < minsilence % 静音还不够长，尚未结束
            count  = count + 1;
         elseif count < minlen   % 语音长度太短，认为是噪声
            status  = 0;
            silence = 0;
            count   = 0;
         else                    % 语音结束
            status  = 3;
         end
      end
   case 3,
      break;
   end
end   

count = count-silence/2;
x2 = x1 + count -1;              %记录语音段结束点

subplot(3,1,1)
plot(x)
axis([1 length(x) -1 1])
ylabel('Speech');
line([x1*inc x1*inc], [-1 1], 'Color', 'red');
line([x2*inc x2*inc], [-1 1], 'Color', 'red');

subplot(3,1,2)
plot(amp);
axis([1 length(amp) 0 max(amp)])
ylabel('Energy');
line([x1 x1], [min(amp),max(amp)], 'Color', 'red');
line([x2 x2], [min(amp),max(amp)], 'Color', 'red');

subplot(3,1,3)
plot(zcr);
axis([1 length(zcr) 0 max(zcr)])
ylabel('ZCR');
line([x1 x1], [min(zcr),max(zcr)], 'Color', 'red');
line([x2 x2], [min(zcr),max(zcr)], 'Color', 'red');