The system then determines the power spectral density of {TAIL ~ the audio signal} from {HEAD ~ the calculated power spectral density} of the speech signal 
The system then determines the power spectral density of { TAIL ~ the audio signal } from { HEAD ~ the calculated power spectral density } of the speech signal
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH