Patent ID: 8386245

Claim:
A method of performing an open-loop pitch analysis using a circuitry, the method comprising: obtaining, using the circuitry, a plurality of open-loop pitch candidates including a first open-loop pitch candidate (p_max 1 ), a second open-loop pitch candidate (p_max 2 ) and a third open-loop pitch candidate (p_max 3 ), wherein p_max 1 >p_max 2 >p — max 3 ; obtaining, using the circuitry, a plurality of long-term correlation values, including a first correlation value (max 1 ), a second correlation value (max 2 ) and a third correlation value (max 3 ), for each corresponding one of the plurality of open-loop pitch candidates; selecting, using the circuitry, an initial open-loop pitch (max) from the plurality of open-loop pitch candidates, wherein the long-term correlation value corresponding to max (p_max) has the maximum long-term correlation value among the long-term correlation values; if p_max 2 is less than p_max, setting a first threshold value to a first pre-determined threshold value if an absolute value of a previous pitch less p_max 2 is less than a first pre-determined comparison value and setting the first threshold value to a second pre-determined threshold value if the absolute value of the previous pitch less p_max 2 is not less than the first pre-determined comparison value; if max multiplied by the first threshold value is less than max 2 , setting max to max 2 and p_max to p — max 2 ; if p_max 3 is less than p_max, setting a second threshold value to a third pre-determined threshold value if an absolute value of a previous pitch less p_max 3 is less than a second pre-determined comparison value and setting the second threshold value to a fourth pre-determined threshold value if the absolute value of the previous pitch less p_max 3 is not less than the second pre-determined comparison value; and if max multiplied by the second threshold value is less than max 3 , setting p_max to p_max 3 .