Abstract:

This paper presents a design method for minimizing the sound transmitted through panels. This unique method is based on minimizing the volume velocity of individual segments of a vibrating panel using control loudspeakers. In this manner, each of the control segments of the panel can be controlled separately. The basic acoustic equations governing volume velocity control are presented, and it is shown that, at low frequencies, this method will achieve global sound power reductions in the far field. Further analysis shows that this method will achieve significant sound power reductions (10 dB or more) for values of kL of 3.0 or less, where L is the characteristic dimension of each control segment. Tests conducted in a transmission loss chamber verify the efficacy of volume velocity control using a controller based on the filtered-x control algorithm. This controller allows for control over a frequency band, and results show sound power reductions of 9 dB over a 60-Hz bandwidth. These tests are among the first attempts to use the volume velocity control method over a band of frequencies. The experimental results are verified with numerical simulations. The results show promise that this methodology is an effective way to control broadband, low-frequency sound.