Patent ID: 7848530

Claim:
An apparatus which reduces a noise, wherein the noise has a known cycle and is included in acoustic data, comprising: a gathering unit which gathers, in series, signals of acoustic data; a gain adjusting unit which adjusts a gain of signals of acoustic data gathered by the gathering unit; a storage unit which is constructed to store the signals of acoustic data for at least one cycle of the noise; a first adjusting unit which re-adjusts a gain of the acoustic data obtained by the gain adjusting unit in accordance with a gain of the gain adjusting unit, and generates acoustic data of a substantially constant gain; an updating unit which (i) multiplies the acoustic data gathered by the gathering unit by a first weighted coefficient, (ii) multiplies in phase acoustic data stored in the storage unit by a second weighted coefficient, (iii) adds the two multiplication results, and (iv) updates the acoustic data stored in the storage unit with the added result; a subtraction unit which subtracts the data stored in the storage unit from the acoustic data obtained by the first adjusting unit; and a second adjusting unit which re-adjusts a gain of the acoustic data obtained by the subtraction unit to the gain of the gain adjusting unit, and outputs the re-adjusted acoustic data as acoustic data after noise removal.