Sound propagation across the air/water interface by a critically coupled resonant bubble
Taehwa Lee, Hideo Iizuka
Abstract
Sound transmission across an air/water interface is known to be ineffective due to a large acoustic impedance mismatch. Efficient sound transmission across an interface between acoustically different media can improve acoustic systems. Here, we demonstrate efficient sound transmission and radiation across an air/water interface using resonant circular bubbles close to the interface. We find that perfect sound transmission is realized under the critical coupling condition, where radiation leakages into air and water are equal. In addition, without incident waves, a resonant bubble as a radiation source exhibits very high sound radiation to air, exceeding sound radiation to water for shallow depths. Moreover, we observe multiresonance sound transmission based on high-order resonance modes in bubbles with a thin elastic shell. Our results provide a critical understanding of the roles of resonant bubbles for sound transmission across an air/water interface.