Simulating room transfer functions between transducers mounted on audio devices using a modified image source method

TL;DR

This paper extends the image source method to include transducer directivity and diffraction effects, enabling more accurate room transfer function simulations for devices with mounted microphones and speakers.

Contribution

The authors introduce a modified ISM using spherical harmonic coefficients to model diffraction effects of mounted transducers, improving simulation accuracy for practical audio device configurations.

Findings

The method accurately simulates room transfer functions for various device configurations.

A simplified version reduces computational load while maintaining accuracy.

The approach outperforms existing ISM techniques in modeling real-world scenarios.

Abstract

The image source method (ISM) is often used to simulate room acoustics due to its ease of use and computational efficiency. The standard ISM is limited to simulations of room impulse responses between point sources and omnidirectional receivers. In this work, the ISM is extended using spherical harmonic directivity coefficients to include acoustic diffraction effects due to source and receiver transducers mounted on physical devices, which are typically encountered in practical situations. The proposed method is verified using finite element simulations of various loudspeaker and microphone configurations in a rectangular room. It is shown that the accuracy of the proposed method is related to the sizes, shapes, number, and positions of the devices inside a room. A simplified version of the proposed method, which can significantly reduce computational effort, is also presented. The proposed method and its simplified version can simulate room transfer functions more accurately than currently available image source methods and can aid the development and evaluation of speech and acoustic signal processing algorithms, including speech enhancement, acoustic scene analysis, and acoustic parameter estimation.