Speaker Direction-of-Arrival Estimation Based on Orthogonal Dipoles

The small aperture microphone array becomes more and more popular in the consumer electronics. However, the small aperture usually limits the performance of the traditional DoA estimation methods. The differential microphone array (DMA) has attracted much attention, recently. The DMA has the frequency-independent beampatterns owing to the small size and the dipole is one of the basic types. In this paper, we investigate the relationship between the direction-of-arrival (DoA) and the dipole beampatterns. It shows that the DoA can be directly yielded by an orthogonal dipole pair for the small aperture microphone array. Based on this relationship, we propose a speaker DoA estimation method with orthogonal dipoles (OD). The OD exhibits a good performance to DoA estimation. Nevertheless, it is vulnerable to the axial directions in the reverberant environment. To increase the robustness to the axial directions, we introduce the anti-reverberation function in OD and propose the improved OD method. Both simulations and experiments show that the proposed methods not only significantly outperform the traditional methods but also are much more computationally efficient without the spatial spectrum search.