Investigating auditory perception and cognition in realistic, controlled environments is made possible by virtual reality (VR). However, when visual information is presented, sound localization results from multimodal integration. Additionally, using head-mounted displays leads to a distortion of visual egocentric distances. With two different paradigms, we investigated the extent to which different visual scenes influence auditory distance perception, and secondary presence and realism. To be more precise, different room models were displayed via HMD while participants had to localize sounds emanating from real loudspeakers. In the first paradigm, we manipulated whether a room was congruent or incongruent to the physical room. In a second paradigm, we manipulated room visibility - displaying either an audiovisual congruent room or a scene containing almost no spatial information- and localization task. Participants indicated distances either by placing a virtual loudspeaker, walking, or verbal report. While audiovisual room incongruence had a detrimental effect on distance perception, no main effect of room visibility was found but an interaction with the task. Overestimation of distances was higher using the placement task in the non-spatial scene. The results suggest an effect of visual scene on auditory perception in VR implying a need for consideration e.g. in virtual acoustics research.

In this paper we consider an in-ear headphone equipped with an inner microphone and multiple loudspeakers and we propose an optimization procedure with a convex objective function to derive a fixed multi-loudspeaker ANC controller aiming at minimizing the sound pressure at the ear drum. Based on the virtual microphone arrangement (VMA) technique and measured acoustic paths between the loudspeakers and the ear drum, the FIR filters of the ANC controller are jointly optimized to minimize the power spectral density at the ear drum, subject to design and stability constraints. For an in-ear headphone with two loudspeakers, the proposed multi-loudspeaker VMA controller is compared to two single-loudspeaker VMA controllers. Simulation results with diffuse noise show that the multi-loudspeaker VMA controller effectively improves the attenuation by up to about 10 dB for frequencies below 300 Hz when compared to both single-loudspeaker VMA controllers.

As an alternative to traditional artificial heads, it is possible to synthesize individual head-related transfer functions (HRTFs) using a so-called virtual artificial head (VAH), consisting of a microphone array with an appropriate topology and filter coefficients optimized using a narrowband least squares cost function. The resulting spatial directivity pattern of such a VAH is known to be sensitive to small deviations of the assumed microphone characteristics, e.g., gain, phase and/or the positions of the microphones. In many beamformer design procedures, this sensitivity is reduced by imposing a white noise gain (WNG) constraint on the filter coefficients for a single desired look direction. In this paper, this constraint is shown to be inappropriate for regularizing the HRTF synthesis with multiple desired directions and three alternative different regularization approaches are proposed and evaluated. In the first approach, the measured deviations of the microphone characteristics are taken into account in the filter design. In the second approach, the filter coefficients are regularized using the mean WNG for all directions. The third approach additionally takes into account several frequency bins into both the optimization and the regularization. The different proposed regularization approaches are compared using analytic and measured transfer functions, including random deviations. Experimental results show that the approach using multiple frequency bands mimicking the spectral resolution of the human auditory system yields the best robustness among the considered regularization approaches.