clear

clc

%在噪聲環境下語音信號的增強

%語音信號為讀入的聲音文件

%噪聲為正態隨機噪聲

sound=wavread('c12345.wav');

count1=length(sound);

noise=0.05*randn(1,count1);

for i=1:count1

signal(i)=sound(i);

end

for i=1:count1

y(i)=signal(i)+noise(i);

end

%在小波基'db3'下進行一維離散小波變換

[coefs1,coefs2]=dwt(y,'db3'); %[低頻 高頻]

count2=length(coefs1);

count3=length(coefs2);

energy1=sum((abs(coefs1)).^2);

energy2=sum((abs(coefs2)).^2);

energy3=energy1+energy2;

for i=1:count2

recoefs1(i)=coefs1(i)/energy3;

end

for i=1:count3

recoefs2(i)=coefs2(i)/energy3;

end

%低頻系數進行語音信號清濁音的判別

zhen=160;

count4=fix(count2/zhen);

for i=1:count4

n=160*(i-1)+1:160+160*(i-1);

s=sound(n);

w=hamming(160);

sw=s.*w;

a=aryule(sw,10);

sw=filter(a,1,sw);

sw=sw/sum(sw);

r=xcorr(sw,'biased');

corr=max(r);

%為清音（unvoice）時，輸出為1；為濁音（voice）時，輸出為0

if corr>=0.8

output1(i)=0;

elseif corr<=0.1

output1(i)=1;

end

end

for i=1:count4

n=160*(i-1)+1:160+160*(i-1);

if output1(i)==1

switch abs(recoefs1(i))

case abs(recoefs1(i))<=0.002

recoefs1(i)=0;

case abs(recoefs1(i))>0.002 & abs(recoefs1(i))<=0.003

recoefs1(i)=sgn(recoefs1(i))*(0.003*abs(recoefs1(i))-0.000003)/0.002;

otherwise recoefs1(i)=recoefs1(i);

end

elseif output1(i)==0

recoefs1(i)=recoefs1(i);

end

end

%對高頻系數進行語音信號清濁音的判別

count5=fix(count3/zhen);

for i=1:count5

n=160*(i-1)+1:160+160*(i-1);

s=sound(n);

w=hamming(160);

sw=s.*w;

a=aryule(sw,10);

sw=filter(a,1,sw);

sw=sw/sum(sw);

r=xcorr(sw,'biased');

corr=max(r);

%為清音（unvoice）時，輸出為1；為濁音（voice）時，輸出為0

if corr>=0.8

output2(i)=0;

elseif corr<=0.1

output2(i)=1;

end

end

for i=1:count5

n=160*(i-1)+1:160+160*(i-1);

if output2(i)==1

switch abs(recoefs2(i))

case abs(recoefs2(i))<=0.002

recoefs2(i)=0;

case abs(recoefs2(i))>0.002 & abs(recoefs2(i))<=0.003

recoefs2(i)=sgn(recoefs2(i))*(0.003*abs(recoefs2(i))-0.000003)/0.002;

otherwise recoefs2(i)=recoefs2(i);

end

elseif output2(i)==0

recoefs2(i)=recoefs2(i);

end

end

%在小波基'db3'下進行一維離散小波反變換 

output3=idwt(recoefs1, recoefs2,'db3');

%對輸出信號抽樣點值進行歸一化處理

maxdata=max(output3);

output4=output3/maxdata;

%讀出帶噪語音信號，存為'101.wav'

wavwrite(y,5500,16,'c101'); 

%讀出處理后語音信號，存為'102.wav'

wavwrite(output4,5500,16,'c102');