Patent ID: 7448382

Claim:
An apparatus for delivering a flow of gas to the airway of a patient the apparatus comprising: (a) a housing; (b) gas flow generating means for providing disposed in the housing and adapted to generate a flow of a gas; (c) gas delivery means adapted to be coupled to the gas flow generating generator means and adapted to be coupled to a patient for communicating the flow of gas with an airway of such a patient; and (d) means for minimizing acoustic noise of the gas flow generating means by generating a cancellation frequency that at least partially cancels acoustic waves generated by the gas flow generating means, wherein the means for minimizing acoustic noise includes a speaker operatively coupled to the housing and adapted to create cancellation acoustic waves at a cancellation frequency, and wherein the speaker is operatively coupled to the housing so as to direct the cancellation acoustic waves into over an area outside the housing such that the cancellation frequency reduces acoustic noise resulting from operation of the gas flow generating means, the reduction of the acoustic noise being at a location outside the housing.