Abstract: An acoustic source apparatus has a acoustic transducer that is enclosed in substantially rigid and watertight enclosure to resist the pressure of water on the transducer and to seal the transducer from the water. The enclosure has an opening through which acoustic signals pass and over which is placed a resilient, expandable and substantially water-impermeable diaphragm. A net stiffens and strengthens the diaphragm as-well-as constrains the diaphragm from overexpansion or from migrating due to buoyancy forces. Pressurized gas, regulated at slightly above ambient pressure, is supplied to the enclosure and the diaphragm to compensate for underwater ambient pressures. Gas pressure regulated at above ambient pressure is used to selectively tune the pressure levels within the enclosure and diaphragm so that diaphragm resonance can be achieved. Controls are used to selectively fill, as-well-as vent the enclosure and diaphragm during system descent and ascent, respectively.

Abstract: An acoustic source apparatus has a loudspeaker enclosed within a substantly pressure resistant and water tight enclosure. Acoustic energy from the loudspeaker emanates through an opening in the enclosure. This opening is covered by a resilient diaphragm that transmits the acoustic energy to an aqueous medium. A net constrains the diaphragm to a preselected size and shape. The net further impedes overexpansion of the diaphragm and restrains the diaphragm from migrating due to buoyancy. Additonally, the net stiffens and strengthens the diaphragm, to thereby increase the resonant frequency, impedance and quality factor of the transducer system and decrease the transmission bandwidth of the system. Constraining the transducer diaphragm with the net makes higher transducer source levels possible.

Abstract: A low frequency, high powered underwater sound source includes a housing ing disposed therein, a loudspeaker, a bladder disposed over the loudspeaker for containing a pressurized non-liquid sound transmission medium, a fill system for filling the bladder with a sound transmission medium, a vent system for venting the bladder of a sound transmission medium, a differential pressure sensor for comparing the pressure in the bladder with the ambient underwater pressure, a signal generating system to generate an acoustic signal at the loudspeaker, and a control system for controlling operation of the fill system, the vent system, the differential pressure sensor and the signal generating system.

Abstract: A method and apparatus for treatment of tissue located in a specified reg of a mammal, the region being proximate to a gas filled cavity which is contained in a fluid medium within the mammal. The resonance frequency of the cavity is determined, and an acoustic signal having a frequency which is equal to the resonance frequency is directed upon the cavity to resonate the cavity, at a selected level of intensity, until a first phase of treatment has been concluded. Thereupon, a selected second phase in the treatment of the tissue is performed.

Abstract: An improvement for a transducer provides an improved operational charactetic for the transmission and reception of acoustic energy in a liquid medium. A rigid shell having an open end and a closed end is vertically oriented to contain a transducer disposed in a portion of the liquid medium. Inside the shell and in direct contact with the surface of the portion of liquid is a gas filled chamber. The transducer and chamber acoustically cooperate to heterodyne transmitted or received acoustic energy. Difference and sum frequencies optionally are selected for data processing. The frequencies of the heterodyned signals are changed by changing the dimensions of the gas filled chamber. Thus, the relatively small transducer is capable of broadband and low frequency transmission.