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