Gradient Impedance Matching Layers Enable Broadband Water-Air Sound Transmission

TL;DR

This paper introduces a gradient impedance matching layer using metafluids to enable broadband sound transmission across water-air interfaces, significantly improving energy transfer and communication capacity.

Contribution

It presents a novel exponential gradient impedance matching layer design with metafluids, achieving broadband water-air sound transmission beyond narrow resonance-based methods.

Findings

Achieved over 16.7dB sound energy transmission enhancement from 880Hz to 1760Hz.

Validated the matching layer in a water tank with experimental results.

Demonstrated multicolor picture transmission across water-air interface.

Abstract

Efficient sound transmission across the water-air interface has always been expected in the field of ocean exploration. However, the existing researches are mainly concentrated on the narrow-band transmission based on resonance, which greatly limits the transmission capacity and efficiency. Here, we combined the air-based and water-based metafluids to realize an exponential gradient impedance matching layer for broadband water-air sound transmission. By cooperatively adjusting the sound velocity and thickness in the matching layers, we modulated the required acoustic parameters of each layer into a reasonable range, which can be conveniently achieved by the proposed metafluids. A matching layer sample was constructed and validated in a water tank. Experimental results show that the proposed matching layer can achieve an average sound energy transmission enhancement above 16.7dB from 880Hz to 1760Hz across the water-air interface. Moreover, we use the proposed matching layer to demonstrate a multicolor picture transmission from air to water, which shows extremely high communication capacity and accuracy. Our work is promising for more applications based on water-air transmission and opens a new avenue to the design and implementation of the extreme impedance matching case.