Patent ID: 6944303
Filing Date: 2005-09-13
Classification: G10K,H03B

Abstract:
1. A noise cancellation device that generates a canceling sound for canceling noise having a particular frequency, comprising: a first signal-generating unit that generates a sine wave signal having substantially the same frequency as the noise; a second signal-generating unit that generates a cosine wave signal whose phase is shifted by 90 degrees with respect to the sine wave signal, the second signal-generating unit comprising an all-pass filter; a first gain-adjusting unit that adjusts the gain of the sine wave signal; a second gain-adjusting unit that adjusts the gain of the cosine wave signal; a combining unit that combines the output signals of the first gain-adjusting unit and the second gain-adjusting unit; a speaker that produces sound corresponding to the output of the combining unit in a predetermined space; a microphone installed at a listening position in the predetermined space; and a gain-controlling unit that controls the gains of the first gain-adjusting unit and the second gain-adjusting unit, respectively, to minimize the output level of the microphone; wherein the all-pass filter shifts a signal inputted into the all-pass filter by 90 degrees with respect to a cut-off frequency of the all-pass filter set to coincide with the particular frequency.