Supervised Direct-Path Relative Transfer Function Learning for Binaural Sound Source Localization

Direct-path relative transfer function (DP-RTF) refers to the ratio between the direct-path acoustic transfer functions of two channels. Though DP-RTF fully encodes the sound directional cues and serves as a reliable localization feature, it is often erroneously estimated in the presence of noise and reverberation. This paper proposes a supervised DP-RTF learning method with deep neural networks for robust binaural sound source localization. To exploit the complementarity of single-channel spectrogram and dual-channel difference information, we first recover the direct-path magnitude spectrogram from the contaminated one using a monaural enhancement network, and then predict the DP-RTF from the dual-channel (enhanced-) intensity and phase cues using a binaural enhancement network. In addition, a weighted-matching softmax training loss is designed to promote the predicted DP-RTFs to be concentrated for the same direction and separated for different directions. Finally, the direction of arrival (DOA) of source is estimated by matching the predicted DP-RTF with the ground truths of candidate directions. Experimental results show the superiority of our method for DOA estimation in the environments with various levels of noise and reverberation.