The perforated panels are widely used in noise control and loudspeaker systems. Besides the inner acoustic impedance of each aperture, the interactions among apertures have some effects on the acoustic impedance of
the perforated panel. The previous studies on the acoustic impedance of the perforated panel use the following three methods: the simplified analytical methods, the experimental methods and the numerical methods. The aforesaid
analytical methods and experimental methods are limited due to some special restrictions. Although the numerical methods can predict the acoustic impedance of the perforated panel accurately, it is not convenient in practica
situations. A simple analytical model is proposed to simulate the acoustic impedance of the perforated panel. Considering each aperture in the perforated panel as a sound source, the total sound field radiated by the system is
the sum of each individual sound field radiated by each aperture. The mutual radiation impedance between one aperture and other apertures is obtained on the basis of the self radiation impedance of the aperture. Then the total
impedance of each aperture, including the inner impedance and the radiation impedance, can be obtained. And the total acoustic impedance of the perforated panel can be derived. T he proposed model and the previous model are
applied to simulate the acoustic impedances of two perforated panels with different perforations, and the differences between two models are compared. It is shown that when the frequency increases, the interactions among apertures
become small, and the difference between the acoustic impedances calculated by two models decreases. It is also found that when the distance among apertures increases, the interactions among apertures become small.
The equivalent circuit method is used to calculate the frequency responses of actual loudspeaker systems with the perforated panels in front of the loudspeakers, and the acoustic impedances of the perforated panels are calculated
with both of the mentioned two models. The frequency responses of the actual loudspeaker systems are also measured in an anechoic chamber. For the loudspeaker system with a single aperture in the perforated panel, both of
the simulated frequency responses are similar to the experimental results. For the loudspeaker system with three or seven apertures in the perforated panel, the simulated frequency response calculated by the proposed model is closer
to the experimental result, and the other simulated frequency response calculated by the previous model diverges a lot from the experimental result, especially for the resonant frequency in the medium- high frequency range. And
the resonant frequency is determined by the acoustic reactance of the perforated panel and the acoustic compliance of the front cavity. It is confirmed that the proposed model is more accurate as the interactions among apertures have
large effects on the acoustic impedance of the perforated panel when the distance between apertures is not large.
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Footnotes
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