Control of Traveling Bending Waves in A Ring Strip Speaker

Abstract

A strip speaker adopts a thin beam as the sound radiator controlled by the traveling-wave control method (TCM) using a small number of array actuators. The previous works investigate the strip speaker consisting of a straight beam and three actuators: the primary actuator acting as a wave source at the middle of the beam and two control actuators near the beam edges to eliminate the reflected bending waves. In this work, the TCM -controlled strip speaker adopts a closed -ring strip without the structural boundary to further reduce the actuators. The bending wave continuously propagating along the ring periphery exhibits similar characteristics to an infinite beam. The ring strip is considered the straight beam of which both edges are connected, thus requiring a single control actuator only. The control result reveals that two actuators are enough to suppress the structural resonances, radiating a smooth sound spectrum. The directivity of radiated sound field depends on actuator configuration due to the axisymmetry of bending wavefield on a ring. Based on the present work, one can design a ring strip structure to be a novel acoustic transducer satisfying the desired performance.