vad.m

语音信号端点检测的实验研究论文,希望对大家有点帮助

function [x1,x2] = vad(x) 
 global x
%幅度归一化到[-1,1] 
x = double(x); 
x = x / max(abs(x)); 
 
%常数设置 
FrameLen = 240; 
FrameInc = 80; 
 
amp1 = 10; 
amp2 = 2; 
zcr1 = 10; 
zcr2 = 5; 
 
maxsilence = 8;  % 6*10ms  = 30ms 
minlen  = 15;    % 15*10ms = 150ms 
status  = 0; 
count   = 0; 
silence = 0; 
 
%计算过零率 
tmp1  = enframe(x(1:end-1), FrameLen, FrameInc); 
tmp2  = enframe(x(2:end)  , FrameLen, FrameInc); 
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, FrameInc)), 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 
x1 = 0;  
x2 = 0; 
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); 
         status  = 2; 
         silence = 0; 
         count   = count + 1; 
      elseif amp(n) > amp2 | ... % 可能处于语音段 
             zcr(n) > zcr2 
         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 | ...     % 保持在语音段 
         zcr(n) > zcr2 
         count = count + 1; 
      else                       % 语音将结束 
         silence = silence+1; 
         if silence < maxsilence % 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; 
 
subplot(311) 
plot(x) 
axis([1 length(x) -1 1]) 
ylabel('Speech'); 
line([x1*FrameInc x1*FrameInc], [-1 1], 'Color', 'red'); 
line([x2*FrameInc x2*FrameInc], [-1 1], 'Color', 'red'); 
 
subplot(312) 
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(313) 
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');
%%%%%%%%%%%%%%%一种计算语音过零率,短时能量,以及端点检测算法