US Patent 7372776 Modal acoustic array transduction apparatus

A transduction apparatus, which employs an array of individual transducers that generates multiple acoustic radiation modes, is described. These modes are used together to yield directional steered beam patterns. In one embodiment separate transducers, clustered in the form of a ring array, are used together to generate wide and narrow cardioid type beam patterns through combined monopole, dipole and quadrupole radiation modes in the medium, along with at least one tail mass.