| 摘要 |
PROBLEM TO BE SOLVED: To shorten the processing time and save the power consumption by using an analong circuit capable of executing sum-of-product operation at a high speed for correlation operation and speeding up pitch detection. SOLUTION: An input sound signal is converted into a digital signal by an A/D converter 1 and the digital signal is inputted to shift register circuits 31, 32, delayed and outputted as plural tap outputs. Delayed digital signals outputted from the taps of the shift registers are inputted to a weighting synthetic circuit 4 to execute the weighted synthetic operation of the analog input sound signal. The initial value of the operation output is held in a sampling/ holding circuit 5 and its peak value is stored in a maximum value storage 6. The sampled/held value and a judgement threshold are mutually multiplied by a multiplier 7 and the multiplied result is compared with the peak value by a judging device 9, and when the peak value is larger than the threshold, a silence/voiced sound changing switch 10 is switched to the voiced sound side. A sound pitch can be detected by measuring delay time from the initial time of the output of the weighted synthetic operation up to the peak value by a counter 8. |
