Real Time High Accuracy 3-D PHAT-Based Sound Source Localization Using a Simple 4-Microphone Arrangement

This paper investigates wideband sound source localization in outdoor cases. In such cases, time difference of arrival (TDOA)-based methods are commonly used for 2-D and 3-D wideband sound source localization. These methods have lower accuracy in comparison with direction of arrival-based approaches. However, they feature fewer microphones and less computation time. High accuracy sound source localization using these methods needs highly accurate time delay measurement, and therefore, high frequency signal sampling rates. Moreover, the need to use numerical analysis methods for local calculations (solving nonlinear equations of closed-form methods) will increase computation time while the calculations may still not converge. Also, a good initial guess close to the true solution is needed to avoid local minima. In this paper, a simple, fast (real time) and accurate pure geometric phase transform-based exact location calculation approach for 3-D localization of wideband sound sources in outdoor far-field and low degree reverberation cases, using only four microphones, is proposed. Based on the proposed method, a simple arrangement of microphones is implemented. Experimental results show that the proposed method has more accuracy and less computation time simultaneously, in comparison with previous closed-form hyperbolic intersection and other TDOA-based state-of-the-art location calculation methods, overcoming their major weaknesses. Also, as the nonlinear closed-form equations are linearized, no initial guess is required. It features less than 0.2^° error for angle of arrival, less than 5% error for 3-D location finding, and computation times as low as 250 ms for the localization of a typical wideband sound source such as a flying object (helicopter).