ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

1pNS3. Active control of sound transmission through a thin metal plate.

Xiaoqi Bao

Vasundara V. Varadan

Vijay K. Varadan

Dept. of Eng. Sci. and Mech., Penn State Univ., University Park, PA 16802

The performance of active sound isolation by using a piezoelectric sensor and an actuator on a thin plate is investigated experimentally. In the experiment, the aluminum plate covers an opening of an acoustic enclosure, where a sound source is located. The outside acoustic field is measured by an 11-element microphone array, which scans on a surface of a hemisphere. The isolation performance of the original plate is poor at its resonance frequencies. The sound transmission from inside to outside of the enclosure is actively controlled by a one-sensor one-actuator control system which minimizes the output of the on-plate sensor. Global reductions of 15--20 dB are achieved at the first three resonance frequencies.