Real-Time Estimation of Direction of Arrival of Speech Source Using Three Microphones.

In this paper, we present a real-time noise-robust direction of arrival (DOA) estimation technique using only the three built-in microphones of the modern Android-based smartphone. The proposed method eliminates the 'front-back' ambiguity caused by the symmetry of the two microphones reported previously and improves the performance of DOA estimation in noisy speech environments. Our method enhances the spatial awareness of hearing-impaired users by displaying the precise DOA angle of speech source on their smartphone screen. For increased efficiency, noise-robustness, and accuracy of the proposed DOA estimation method, a spectral pre-filtering technique and a Voice Activity Detector (VAD) based post-filtering are used along with a modified generalized cross-correlation (GCC) technique. Real recorded and simulated data under realistic noisy conditions are used in the evaluations of the proposed algorithm. Real-time implementation of the proposed system is carried out on an Android-based smartphone without any additional hardware or external microphone attachments. Experimental results show the performance of the proposed method versus those without pre or post-filtering under three different noisy conditions with 0dB to 10dB signal to noise ratios (SNRs).