Patent ID: 7757808

Claim:
A noise reduction system for a device comprising a noise generating subsystem, the noise reduction system comprising: a Helmholtz resonator disposed in fluid communication with the noise generating subsystem, the Helmholtz resonator comprising a neck, and a resonance volume comprising a wall, at least one of the neck and the wall being formed from an active material responsive to a control signal that adjusts a dimensional characteristic of the Helmholtz resonator in such a manner as to affect a resonance characteristic of the Helmholtz resonator; and a controller responsive to an operational characteristic of either the device or the noise generating subsystem to produce the control signal; wherein in response to the operational characteristic, the control signal serves to affect the resonance characteristic of the Helmholtz resonator in such a manner as to reduce a noise arising from the noise generating subsystem, or create a desirable sound quality alteration.