###### Abstract  
As an alternative to conventional artificial heads, a virtual artificial head (VAH), i.e., a microphone array-based filter-and-sum beamformer, can be used to create binaural renderings of spatial sound fields. In contrast to conventional artificial heads, a VAH enables one to individualize the binaural renderings and to incorporate head tracking. This can be achieved by applying complex-valued spectral weights--calculated using individual head related transfer functions (HRTFs) for each listener and for different head orientations--to the microphone signals of the VAH. In this study, these spectral weights were applied to measured room impulse responses in an anechoic room to synthesize individual binaural room impulse responses (BRIRs). In the first part of the paper, the results of localizing virtual sources generated with individually synthesized BRIRs and measured BRIRs using a conventional artificial head, for different head orientations, were assessed in comparison with real sources. Convincing localization performances could be achieved for virtual sources generated with both individually synthesized and measured non-individual BRIRs with respect to azimuth and externalization. In the second part of the paper, the results of localizing virtual sources were compared in two listening tests, with and without head tracking. The positive effect of head tracking on the virtual source localization performance confirmed a major advantage of the VAH over conventional artificial heads. virtual acoustics; sound localization; dynamic binaural rendering +
Footnote †: journal: Medical Physics and Acoustics, Carl von Ossietzky University of Oldenburg, Carl-von-Osietzky-Strasse 11, 26129 Oldenburg, Germany; [EMAIL_ADDRESS]  
Footnote †: journal: Medical Physics and Acoustics, Carl von Ossietzky-Strasse 11, 26129 Oldenburg, Germany; [EMAIL_ADDRESS]  
Footnote †: journal: Medical Physics and Acoustics, Carl von Ossietzky University of Oldenburg, Carl-von-Osietzky-Strasse 11, 26129 Oldenburg, Germany; [EMAIL_ADDRESS]  
Footnote †: journal: Medical Physics and Acoustics, Carl von Ossietzky-Strasse 11, 26129 Oldenburg, Germany; [EMAIL_ADDRESS]  
Footnote †: journal: Medical Physics and Acoustics, Carl von Ossietzky University of Oldenburg, Carl-von-Osietzky-Strasse 11, 26129 Oldenburg, Germany; [EMAIL_ADDRESS]  
Footnote †: journal: Medical Physics and Acoustics, Carl von Ossietzky-Strasse 11, 26129 Oldenburg, Germany; simon. to achieve similar localization performances with dynamically presented virtual sources and real sources [6; 7; 8]. This study aimed to assess the localization performance when listening to virtual sources generated with virtual artificial head (VAH) technology [9; 10]. A VAH, as an alternative to conventional artificial heads, is a microphone array using filter-and-sum beamforming in order to synthesize the directivity patterns of individual left and right HRTFs. This is done by applying complex-valued spectral weights to the microphone signals and adding them. In [9; 10; 11], it was proposed to calculate the spectral weights by minimizing a least-squares-based narrow-band cost function, which measures the deviation between the desired and the synthesized HRTF directivity patterns. In order to achieve a small synthesis error, the cost function is minimized, subject to constraints imposed on the spectral error in a number of directions. An additional constraint is applied to the mean white noise gain to increase the robustness. Compared to conventional artificial heads, the VAH offers not only the possibility to adjust to individual HRTFs by using individually optimized spectral weights, but also the possibility to adjust to different head orientations during playback. This can be achieved by calculating spectral weights for different head orientations, such that the same recording, captured for a single orientation of the VAH during the recording, can be presented dynamically during playback, i.e., with head tracking.