Testing a hydroacoustic radiator in a reverberant tank based on recording the sound field in the air above the tank

TL;DR

This paper presents a calibration method for monopole sound sources in water tanks using air sound field measurements, exploiting the water-air boundary's filtering effect to estimate source strength.

Contribution

It introduces a novel calibration technique leveraging the water-air boundary's transparency for shallow sources, enabling accurate source strength estimation from air recordings.

Findings

The water-air boundary acts as a filter for reflected waves.

The method allows calibration without direct water measurements.

Analytical formulas enable estimation of source strength from air sound levels.

Abstract

A method for calibrating a monopole sound source in a water tank with reflective side walls and bottom is considered. The idea of the method is based on the phenomenon of anomalous transparency of the water-air boundary for a sound source located at a shallow depth. This boundary plays the role of a filter that prevents waves reflected from the side walls and bottom from entering the air. For a shallow source, the field in the air will be approximately the same as for a source located at the same depth in a homogeneous water half-space. This field is described by a well-known analytical formula that makes it possible to estimate the source strength in water based on the sound intensity level measured in air.