Patent ID: 8634276

Claim:
A sound source, comprising: a bubble configured to be filled with a gas; a volume velocity actuator configured to perturb the gas within the bubble by changing a volume of the gas without adding gas to or removing gas from the bubble; a processing circuit configured to provide a source control signal to the volume velocity actuator to cause the volume velocity actuator to perturb the gas within the bubble at a frequency defined by the source control signal; and a resonant frequency control mechanism configured to keep a resonant frequency and a phase of a radiated signal of the sound source approximately equal to a frequency and a phase of the source control signal, wherein the resonant frequency control mechanism comprises: a rigid fixed member; at least one rigid movable member configured to move relative to the fixed rigid member, the at least one rigid movable member disposed substantially along an axis of the fixed rigid member, wherein the rigid movable member is coupled to a member actuator; and wherein the processing circuit is configured to provide a member control signal to the member actuator to move the at least one rigid movable member.