Quantitative analysis of low frequency acoustic characteristics for reverse horn by bottleneck effect analogy method

摘要

Reverse horn as one of the Acoustic Black Hole (ABH) structures can be used to effectively reduce low frequency acoustic waves by focusing the sound energy. The sound waves in relatively low frequency range are focused on the tip of reverse horn, and most sound energy cannot flow out from the reverse horn's tip. In this paper, we propose a quantitative analysis method by the bottleneck effect analogy to research the low frequency acoustic characteristics of reverse horn. Our theoretical results show that the low frequency sound wave can be focused on the tip of reverse horn, and the transmission coefficient of low frequency is proportional to the 3 power law of the reverse horn tip's diameter. The experimental results verified our theoretical results. And the sound insulation property is studied by experiments. It is noteworthy that the insulation coefficient of two levels reverse horn whose second level tip's diameter d = 12 mm, is more than 0.92, and can increase further with the decrease of the second level horn tip's diameter. It provides an effective and simple method for quantitatively analyzing the low frequency acoustic characteristics of the reverse horn. The proposed reverse horn has great potential applications for low frequency sound insulation control.