Patent ID: 8204239

Claim:
An audio processing method comprising: writing, in a memory, at least one sample of a signal component having a first frequency less than a predetermined frequency in an input audio signal that is a digital signal having a predetermined sampling frequency; and generating a harmonic-overtone signal having a second frequency, wherein the second frequency is equal to N multiplied by a third frequency of the input audio signal, by repeating an operation N times, where N is an integer greater than or equal to one, the operation including reading one sample and thinning out (N−1) samples for every N samples of the at least one sample from the memory within a cycle period from a first one-direction zero-crossing point to a second one-direction zero-crossing point subsequent to the first one-direction zero-crossing point, wherein both first and second one-direction zero-crossing points are upward one-direction zero-crossing points at which a level of the input audio signal changes from negative to positive or both first and second one-direction zero-crossing points are downward one-direction zero-crossing points at which the level of the input audio signal changes from positive to negative.