%谱减法语音增强
%输入参数s 语音数据,fs 采样频率,p 下面有说明,共11个,可不输入,有默认值
%“过度减法(oversubtraction)”作减法的时候,保留一小部分原来的背景噪音,用这部分背景噪音来掩盖住音乐噪音的谱峰,从而消除了令人不悦的音乐噪音。
%通过给的参数p,估计噪音,做谱减法。从而消除噪音。
function [ss,po]=specsubm(s,fs,p)
%利用频谱相减(spectral subtraction)增强 [SS,PO]=(S,FS,P)
%
% implementation of spectral subtraction algorithm by R Martin (rather slow)
% algorithm parameters: t* in seconds, f* in Hz, k* dimensionless
% 1: tg = smoothing time constant for signal power estimate (0.04): high=reverberant, low=musical
% 2: ta = smoothing time constant for signal power estimate
%
used in noise estimation (0.1)
% 3: tw = fft window length (will be rounded up to 2^nw samples)
% 4: tm = length of minimum filter (1.5): high=slow response to noise increase, low=distortion
% 5: to = time constant for oversubtraction factor (0.08)
% 6: fo = oversubtraction corner frequency (800): high=distortion, low=musical
% 7: km = number of minimisation buffers to use (4): high=waste memory, low=noise modulation
% 8: ks = oversampling constant (4)
% 9: kn = noise estimate compensation (1.5)
% 10:kf = subtraction floor (0.02): high=noisy, low=musical
% 11:ko = oversubtraction scale factor (4): high=distortion, low=musical
%检查函数的输入参数,如果输入少于三个,po为默认值,po的参数上面有说明
if nargin<3 po=[0.04 0.1 0.032 1.5 0.08 400 4 4 1.5 0.02 4].'else po=pend
ns=length(s)
ts=1/fs
ss=zeros(ns,1)
ni=pow2(nextpow2(fs*po(3)/po(8)))
ti=ni/fs
nw=ni*po(8)
nf=1+floor((ns-nw)/ni)
nm=ceil(fs*po(4)/(ni*po(7)))
win=0.5*hamming(nw+1)/1.08win(end)=[]
zg=exp(-ti/po(1))
za=exp(-ti/po(2))
zo=exp(-ti/po(5))
px=zeros(1+nw/2,1)
pxn=px
os=px
mb=ones(1+nw/2,po(7))*nw/2
im=0
osf=po(11)*(1+(0:nw/2).'*fs/(nw*po(6))).^(-1)
imidx=[13 21]'
x2im=zeros(length(imidx),nf)
osim=x2im
pnim=x2im
pxnim=x2im
qim=x2im
for is=1:nf
idx=(1:nw)+(is-1)*ni
x=rfft(s(idx).*win)
x2=x.*conj(x)
pxn=za*pxn+(1-za)*x2
im=rem(im+1,nm)
if im
mb(:,1)=min(mb(:,1),pxn)
else
mb=[pxn,mb(:,1:po(7)-1)]
end
pn=po(9)*min(mb,[],2)
%os= oversubtraction factor
os=zo*os+(1-zo)*(1+osf.*pn./(pn+pxn))
px=zg*px+(1-zg)*x2
q=max(po(10)*sqrt(pn./x2),1-sqrt(os.*pn./px))
ss(idx)=ss(idx)+irfft(x.*q)
end
if nargout==0
soundsc([sss],fs)
end
x=[-1.58 0.42 0.46 0.78 -0.49 0.59 -1.3 -1.42 -0.16 -1.47 -1.350.36 -0.44 -0.14 1 -0.5 -0.2 -0.06 -0.6 0.42 -1.52 0.51 0.76 -1.50.16 -1.29 -0.65 -1.48 0.6 -1.65 -0.55]lev=5
wname='db3'
[c,l]=wavedec(x,lev,wname)
sigma=wnoisest(c,l,1)
alpha=2
thr1=wbmpen(c,l,sigma,alpha)
[thr2,nkeep]=wdcbm(c,l,alpha)
xd1=wdencmp('gbl',c,l,wname,lev,thr1,'s',1)
[xd2,cxd,lxd,perf0,perfl2]=wdencmp('lvd',c,l,wname,lev,thr2,'h')
[thr,sorh,keepapp]=ddencmp('den','wv',x)
xd3=wdencmp('gbl',c,l,wname,lev,thr,'s',1)
subplot(411)plot(x)title('原始信号','fontsize',12)
subplot(412)plot(xd1)title('使用penalty阈值降噪后信号','fontsize',12)
subplot(413)plot(xd2)title('使用Birge-Massart阈值降噪后信号','fontsize',12)
subplot(414)plot(xd3)title('使用缺省阈值降噪后信号','fontsize',12)
欢迎分享,转载请注明来源:内存溢出
评论列表(0条)