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