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.