HearLoc: Locating Unknown Sound Sources in 3D With a Small-Sized Microphone Array

Indoor Sound Source Localization (ISSL) is under growing focus with the rapid development of smart IOT intelligence. The predominant approaches typically involve constructing large microphone (Mic) array systems or extracting multiple angles of arrival (AOAs). However, the performance of these solutions is often constrained by the physical size of the array. Besides, there has been limited focus on 3D localization with a single small-sized Mic array. In this paper, we propose HearLoc, an ISSL system that can directly locate 3D sources with a ten-cm Mic array. We demonstrate that the localization ability and dimensional capability can be significantly enhanced by incorporating the time differences of arrival (TDOAs) between the line-of-sight (LOS) and ECHO signals from nearby reflective surfaces. Our approach involves a localization method that selectively sums the correlation powers at useful TDOAs induced by each location. We also design a data processing pipeline with interpolation, normalization and pruning techniques to improve system accuracy and efficiency. To further enhance scalability, we design an iterative algorithm for the ISSL problem with multiple sources and an array location calibration scheme. Experiments demonstrate that the HearLoc can effectively locate sound sources, exhibiting 2x/3.7x improvements in accuracy for 2D and 3D localization, respectively, and a 4x increase in efficiency compared to the existing AOA-based ISSL solutions.