Steered Response Power-Based Direction-of-Arrival Estimation Exploiting an Auxiliary Microphone

TL;DR

This paper introduces a novel DOA estimation method using an auxiliary microphone to improve accuracy in noisy and reverberant environments by computing SRP-PHAT spectra between the auxiliary microphone and the microphone array.

Contribution

It proposes leveraging an auxiliary microphone at an unknown position to enhance DOA estimation with SRP-PHAT, especially under challenging noise and reverberation conditions.

Findings

Auxiliary microphone improves DOA accuracy when properly spaced.

Optimal auxiliary microphone distance depends on noise and reverberation levels.

Validated with simulated signals under various conditions.

Abstract

Accurately estimating the direction-of-arrival (DOA) of a speech source using a compact microphone array (CMA) is often complicated by background noise and reverberation. A commonly used DOA estimation method is the steered response power with phase transform (SRP-PHAT) function, which has been shown to work reliably in moderate levels of noise and reverberation. Since for closely spaced microphones the spatial coherence of noise and reverberation may be high over an extended frequency range, this may negatively affect the SRP-PHAT spectra, resulting in DOA estimation errors. Assuming the availability of an auxiliary microphone at an unknown position which is spatially separated from the CMA, in this paper we propose to compute the SRP-PHAT spectra between the microphones of the CMA based on the SRP-PHAT spectra between the auxiliary microphone and the microphones of the CMA. For different levels of noise and reverberation, we show how far the auxiliary microphone needs to be spatially separated from the CMA for the auxiliary microphone-based SRP-PHAT spectra to be more reliable than the SRP-PHAT spectra without the auxiliary microphone. These findings are validated based on simulated microphone signals for several auxiliary microphone positions and two different noise and reverberation conditions.