Patent ID: 8441892

Claim:
A sound source, comprising: a resonator with an at least partially elastic exterior and configured to be filled with a gas; a volume velocity actuator configured to perturb the gas within the resonator by changing the volume of gas within the resonator; a processing circuit configured to provide a control signal to the volume velocity actuator to cause the volume velocity actuator to perturb the gas within the resonator at a frequency defined by the control signal; and a resonant frequency control mechanism configured to keep a resonant frequency and a phase of a radiated signal of the resonator approximately equal to a frequency and a phase of the control signal, the resonant frequency control mechanism disposed in an interior of the resonator, wherein the resonant frequency control mechanism comprises: at least one rigid movable member coupled to an actuator; and a fixed rigid member containing at least one opening defining a contiguous gas flow path between a first volume and a second volume, wherein the at least one rigid movable member is movable relative to the at least one opening, and wherein at least one dimension of the contiguous gas flow path is determined by the position of the at least one rigid movable member; and a processing circuit configured to provide a control signal to the actuator to move the at least one rigid movable member relative to the at least one opening to adjust the at least one dimension of the contiguous gas flow path.