The system updates an autocorrelation function of the audio signal from {HEAD ~ samples} in the audio signal, estimates an autocorrelation function of {TAIL ~ the speech signal} from the updated autocorrelation function of the audio signal, and calculates a power spectral density of the speech signal using the estimated autocorrelation function 
The system updates an autocorrelation function of the audio signal from { HEAD ~ samples } in the audio signal , estimates an autocorrelation function of { TAIL ~ the speech signal } from the updated autocorrelation function of the audio signal , and calculates a power spectral density of the speech signal using the estimated autocorrelation function
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