The method 8, wherein the calculating a power spectral density of {HEAD ~ the speech signal} using {TAIL ~ the estimated autocorrelation function} comprises: 
The method 8 , wherein the calculating a power spectral density of { HEAD ~ the speech signal } using { TAIL ~ the estimated autocorrelation function } comprises :
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH