Patent ID: 7230176

Claim:
A method comprising: initializing a function f t and a time t, where t=0, x′ 0 =f 0 (F 0 ), x′ 0 is a pitch estimate at time zero and F 0 is a frequency of an acoustic signal at time zero; and determining at least one pitch estimate using the function x′ t =f t (F t ) by an iterative process of creating f t+1 (F t+1 ) based at least partly on pitch estimates x′ t , x′ t−1 , x′ t−2 , x t−3 , . . . , and functions f t (F t ), f t−1 (F t−1 ), f t−2 (F t−2 ), f t−3 (F t−3 ) . . . and incrementing t; calculating at least one final pitch estimate; and at least one of outputting to an input acoustic transducer, or storing in a memory, the acoustic signal processed in accordance with the at least one final pitch estimate.