Patent ID: 9679552
Date: 2017-06-13
CPC Classifications: G10K,H04R

Claim:
1. A system for reducing harmonic noise caused by a plurality of noise sources by causing one or more loudspeakers to produce sounds that are at about the same frequencies as the noise and of substantially opposite phases, the system comprising: a plurality of noise cancellers including a fixed frequency noise canceller and an engine noise canceller, each noise canceller comprising a harmonic sine wave generator that generates an output sine wave having a frequency that corresponds to the noise to be reduced, and an adaptive filter that uses a sine wave to create a noise reduction signal that is used to drive one or more transducers with their output directed to reduce noise caused by the noise sources; and an overlap detector that compares the frequencies of the noise caused by the plurality of noise sources, and, based on the proximity of the frequencies, alters the operation of one or more of the adaptive filters.