Patent ID: RE38889

Claim:
A pitch period extracting apparatus of a speech signal, comprising: an A/D converter for converting a speech signal into speech signal data at a sampling frequency; a memory for storing the speech signal data outputted from said A/D converter: an autocorrelative value calculating means for calculating autocorrelative values of the speech signal data stored in said memory on the basis of delay time s of the speech signal data; a delay time range determining means for determining a range of said delay time s according to said sampling frequency, a period setting means for setting a plurality of delay time ranges periods in the range of the delay time s determined by said delay time range determining means; a product sum range control means for controlling a product sum range s in calculating the autocorrelative values for each of said plurality of delay time ranges periods such that the product sum ranges of said plurality of delay time ranges periods are different from each other; and a pitch period detecting means for detecting a pitch period of said speech signal by evaluating a maximum autocorrelative value out of said autocorrelative values in each of respective delay time ranges all of the periods .