Patent ID: 7696761

Claim:
A distortion detector for detecting distortion in a frequency domain with respect to a time domain signal in a time domain, the distortion detector comprising: a time window processing section for multiplying the time domain signal by a time window so as to output a result of the multiplication; an averaging processing section for averaging the result of the multiplication so as to output a result of the averaging; a time/frequency conversion processing section for converting the result of the averaging into a frequency domain signal according to a predetermined time length; and a distortion extracting section for extracting a distortion component from the frequency domain signal, wherein: the predetermined time length is derived from a unit for performing the time/frequency conversion, the time window has a period having n times the predetermined time length, where n is an integer equal to or larger than 2, and the average processing section makes an average by making an adding calculation n-times at an interval of said predetermined time length within said time window.