Patent ID: 8442240

Claim:
A sound processing apparatus comprising: a power spectrum operation means for obtaining a power spectrum of an audio signal; a pitch detection means for identifying zero or more potential pitches from the power spectrum; an envelope component removal means for removing an envelope component of the power spectrum and generating a signal characteristic that represents a peakness of the power spectrum; a harmonic structure removal means for removing components of frequencies of the signal characteristic that are equal or close to positive integer multiples of a potential pitch when (1) a potential pitch exceeds a processing threshold, and (2) the signal characteristic has a harmonic structure; a time averaging means for generating a time-averaged signal characteristic by averaging the signal characteristic and one or more prior signal characteristics obtained at earlier times from a same input channel; a filter characteristic calculation means for calculating a filter characteristic suppressing the signal characteristic by using the time-averaged signal characteristic; and a suppress filter for filtering the audio signal by using the filter characteristic, wherein the sound processing apparatus suppresses howling.