Pitch period extracting apparatus of speech signal

Abstract

A pitch period extracting apparatus includes a microcomputer which determines a sampling frequency for an A/D converter, and a range of delay times for calculating autocorrelative values on the basis of the sampling frequency. For example, the delay times are set within a range of 20 samples≦k≦100 samples in a case of 8 kHz, and a range of 15 samples≦k≦75 samples in a case of 6 kHz. The microcomputer calculates the autocorrelative values of speech signal data stored in a buffer memory, and outputs a delay time at which a maximum autocorrelative value is obtainable as a pitch period of an inputted speech signal.

1. 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 times of the speech signal data;  
 a delay time range determining means for determining a range of said delay times according to said sampling frequency,  
 a period setting means for setting a plurality of delay time ranges periods in the range of the delay times determined by said delay time range determining means;  
 a product sum range control means for controlling a product sum ranges 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.  
 
     
     
       2. A pitch period extracting apparatus according to  claim 1 , wherein said product sum range control means determines the product sum ranges according to the pitch period to be evaluated. 
     
     
       3. A pitch period extracting apparatus according to  claim 2 , wherein said product sum range control means makes the product sum ranges narrower for the delay time ranges periods in which a longer pitch periods are is evaluated. 
     
     
       4. A pitch period extracting apparatus according to  claim 3 , wherein said product sum range control means sets said product sum range to have an end value different maximum values in each of the plurality of different delay time ranges so it is equal to a different maximum value periods. 
     
     
       5. A pitch period extracting apparatus of a speech signal, comprising:
 an A/D converter for converting a speech signal into speech signal data with 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 times of the speech signal data;  
 a delay time range determining means for determining a range of said delay times according to said sampling frequency;  
 a period setting means for setting a plurality of periods in the range of the delay times determined by said delay time range determining means;  
 a product sum ranges control means for controlling product sum range in calculating the autocorrelative values for each of said plurality of periods such that the product sum ranges of said plurality of 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 all of the periods wherein said period setting means sets a starting value and an end value of each of the plurality of periods in a manner that the end value does not include is less than double the starting value.  
 
     
     
       6. A pitch period extracting apparatus according to claim  2   5 , wherein said product sum range control means sets said product sum ranges to have an end value different maximum values in each of the plurality of different delay time ranges so it is equal to a different maximum value periods. 
     
     
       7. A pitch period extracting apparatus according to  claim 1 , wherein said product sum range control means sets said product sum ranges to have an end value of the product sum range different maximum values in each of the plurality of different delay time ranges so it in equal to a different maximum value periods. 
     
     
       8. A pitch period extracting apparatus according to  claim 2 , wherein said period setting means sets a starting value and an and end value of each of the plurality of delay time ranges periods in a manner such that the end value does not include is less than double the starting value. 
     
     
       9. A pitch period extracting apparatus according to  claim 1 , wherein said period setting means sets a starting value and an end value of each of the plurality of delay time ranges periods in a manner such that the end value does not include is less than double the starting value. 
     
     
       10. 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 times of the speech signal data;  
 a period setting means for setting a plurality of delay time ranges periods in a the range of the delay times ;  
 a product sum range control means for controlling a product sum ranges 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.  
 
     
     
       11. A pitch period extracting apparatus according to  claim 10 , wherein said product sum range control means determines the product sum ranges according to the pitch period to be evaluated. 
     
     
       12. A pitch period extracting apparatus according to  claim 11 , wherein said product sum range control means makes the product sum ranges narrower for the delay time ranges periods in which a longer pitch periods are is evaluated. 
     
     
       13. A pitch period extracting apparatus according to  claim 10 , wherein said product sum range control means sets said product sum ranges to have an end value different maximum values in each of the plurality of different delay time ranges it is equal to a different maximum value periods. 
     
     
       14. A pitch period extracting apparatus of a speech signal according to  claim 10 , wherein said period getting setting means sets a starting value and an and end value of each of the plurality of delay time ranges in a manner that the end value does not include is less than double the starting value. 
     
     
       15. A pitch period extracting apparatus according to  claim 11 , wherein said product sum range control means sets said product sum ranges to have an end value different maximum values in each of the plurality of different delay time ranges so it is equal to a different maximum value periods. 
     
     
       16. A pitch period extracting apparatus according to  claim 10 , wherein said product sum range control means sets said product sum ranges to have an end value different maximum values of the product sum range in each of the plurality of different delay time ranges so it is equal to a different maximum value periods. 
     
     
       17. A pitch period extracting apparatus according to  claim 11 , wherein said period setting means sets a starting value and an end value of each of the plurality of delay time ranges periods in a manner such that the end value does not include is less than double the starting value. 
     
     
       18. A pitch period extracting apparatus according to  claim 10 , wherein said period netting setting means sets a starting value and an and end value of each of the plurality of delay time ranges periods in a manner such that the and end value does not include is less than double the starting value.