Theoretical model and dynamic wave-amplification effect of the high intensity Helmholtz sound source

Abstract

Helmholtz sound source consists of Helmholtz resonator and speaker and belongs to a new type of high-intensity sound source. It has potential industrial advantage in the aerodynamic acoustic application for the large amplitude wave. Based on the lumped parameter principle of acoustic impedance, an acoustic theoretical model is suggested. The model reveals the amplification regulation of the sound source on the acoustic wave. Through the acoustic theoretical computation, a dynamic amplification and an amplification limitation are analyzed. The wave-amplification effect attributes to the parameter regulation of the macro, micro, and dynamic-varied sizes of the sound source. The repetitive motion of the vibrating membrane of speaker causes three working states of balance, squeeze, and stretch. The three states act as specific boundary conditions and demonstrate as three different theoretical curves. The theoretical boundary curves codetermine an experimental curve, which essentially limits the practical amplification effect. Nevertheless, the amplification gain of sound pressure amplitude reaches up to 1.8 times, and the potential maximum amplitude reaches up to 3600 Pa (164 dB). The two quantitative characteristics indicate the maximum capability of the sound source on wave-amplification effect. The control sensitivity of the complicated impedance parameters on wave amplification is 0.26 Pa/Hz. The acoustic theoretical model is valuable in the series aspects of the industrial design, manufacture, and application of the sound source. Especially, the theoretical innovation lays the foundation of solid to these aspects.