Method and apparatus for controlling the sound field in a vehicle cabin or the like
Resonator for internal combustion engines
Silencer with a side branch
Selective active cancellation system for repetitive phenomena
Active sound attenation system for engine exhaust systems and the like
Extended frequency range Helmholtz resonators
Active vibration control Patent #: 5170433
ApplicationNo. 165579 filed on 12/13/1993
US Classes:381/71.14, Tonal noise or particular frequency or band181/206, By wave interference181/228, With exhaust pipe381/71.9Nonacoustically derived reference signal
ExaminersPrimary: Isen, Forester W.
Attorney, Agent or Firm
International ClassG10K 011/16
Foreign Application Priority Data1989-11-24 JP
AbstractA device for cancelling annoying sounds caused by operation of an internal combustion engine. An intake sound of the engine, and also a rotational speed of the engine, are obtained. The phase difference between the present intake sound and a desired intake sound is obtained using map data. The map data depends on the rotational speed of the engine and is specifically calculated so that at least the (n+0.5) harmonics (n integerࣙ0) are cancelled. The phase data is used to drive a ceramic speaker or two oppositely directed ceramic speakers, to appropriately compensate the input sound.