Patent ID: 7783055

Claim:
A method of soundproofing a rack, the method comprising: installing a first duct at an inlet panel of the rack; installing a second duct at an outlet panel of the rack; causing air to flow through the rack in a labyrinth manner from the first duct to the second duct; and providing an active noise control (ANC) system at least partially within at least one of the first and second ducts, wherein the ANC system is to actively reduce one or more effects of a noise generated by a noise source, wherein the ANC system comprises: an input transducer to sense an acoustic noise field generated by the noise source, and to generate an input signal corresponding to the acoustic noise field; an output actuator to generate an acoustic output field effective to reduce a level of the acoustic noise field; a correction unit to adjust the input signal to compensate for characteristics of the input transducer and the output actuator; an echo cancellation unit to remove from the input signal a portion of the output of the output actuator, which comprises a feedback through the input transducer, wherein an output of the echo cancellation unit represents a signal corresponding to the noise source; and an anti-noise generator to generate an anti-noise signal opposite in phase to the input signal, wherein the output actuator is to generate the acoustic output field based on the anti-noise signal.