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.