ASAP: An Azimuth-Priority Strip-Based Search Approach to Planar Microphone Array DOA Estimation in 3D

2026-04-28

AI Summary

This study addresses the high computational complexity of conventional SRP-PHAT methods in three-dimensional direction-of-arrival (3D DOA) estimation, which stems from exhaustive searches over a dense grid of candidate directions and hinders real-time applicability. To overcome this limitation, the authors propose a two-stage strip-based search strategy: first, a coarse-to-fine search within azimuth strips identifies and retains multiple prominent peaks; then, elevation angles are refined along the corresponding great circles. By leveraging the higher reliability of azimuth estimates and integrating geometric search techniques—including spherical cap multi-peak retention, azimuth strip partitioning, and great-circle-based elevation refinement—the method achieves substantial computational savings while preserving estimation accuracy. Simulations and real-world experiments demonstrate that the proposed approach attains comparable precision to state-of-the-art 3D DOA estimators but with significantly improved computational efficiency.

Abstract

Direction-of-arrival (DOA) estimation is an important task in microphone array processing and many downstream applications. The steered response power with phase transform (SRP-PHAT) method has been widely adopted for DOA estimation in recent years. However, accurate SRP-PHAT estimation in 3D scenarios requires evaluating steering responses over thousands of candidate directions, severely limiting real-time performance on resource-constrained platforms. This challenge becomes even more critical for planar arrays, which are widely used in robotics due to their structural simplicity. Motivated by the fact that azimuth estimation is usually more reliable than elevation estimation for most arrays, we propose ASAP, an azimuth-priority strip-based search approach to planar microphone array DOA estimation in 3D. In the first stage, ASAP performs coarse-to-fine region contraction within azimuthal strips to lock azimuth angles while retaining multiple maxima through spherical caps. In the second stage, it refines elevation along the great-circle arc between two close candidates. Extensive simulations and real-world experiments validate the efficiency and merits of the proposed method over existing approaches.

Problem

• DOA estimation
• SRP-PHAT
• planar microphone array
• 3D localization
• real-time performance

Innovation

• DOA estimation
• SRP-PHAT
• azimuth-priority search
• planar microphone array
• 3D localization