Acousto-optic sensing of the sound field in a lightly damped room

摘要

Microphone arrays are a powerful means to capture and analyse the spatio-temporal properties of a sound field. The measurement principle is based on a discrete (point-wise) sampling of the sound field, which makes it ill-suited for measuring over large regions of space, e.g. in rooms or other three-dimensional domains of considerable extent. In this study we introduce a method to measure the sound field in a room using the acousto-optic effect. The sensing principle exploits the fact that acoustic pressure fluctuations induce changes in the refractive index of air, and this makes it possible to sense the acoustic field from optical laser measurements. This is inherently a spatial sensing method that enables to capture the sound field over an extended region of space. Furthermore, the sound field can be measured remotely, reaching locations of the room that are not easily accessible by conventional means. In this study we introduce the reconstruction method and assess the quality of the estimated sound held.