ISBN 9783843949255

978-3-8439-4925-5, Reihe Elektrotechnik

Mina Fallahi
Optimization and Evaluation of a Virtual Artificial Head for Individual Dynamic Spatial Sound Reproduction over Headphones

176 Seiten, Dissertation Carl von Ossietzky Universität Oldenburg (2021), Hardcover, B5

Zusammenfassung / Abstract

As an alternative to artificial heads, a Virtual Artificial Head (VAH) can be used in binaural technology. VAH is a microphone array where spectral weights are applied to the microphone signals to synthesize the directivity pattern of HRTFs. By adjusting the spectral weights, the recorded signals can be individualized and head movements can be accounted for during listening. This thesis aims at improving the performance of a state-of-the-art VAH approach and evaluating it for situations which were considered before. The first focus is to improve the horizontal spatial resolution of the VAH synthesis. The second focus is to investigate the impact of the microphone array topology on the VAH performance. The third focus is to evaluate the VAH approach in dynamic auralizations for horizontal and non-horizontal sources, in anechoic and reverberant environments.We propose a new constrained optimization method to increase the spatial resolution in the horizontal plane. In addition to the constraint on the mean White Noise Gain (WNG) to increase robustness, we propose to impose constraints on the monaural spectral error, referred to as spectral distortion. We show that the frequency range, for which the synthesis accuracy can be considered acceptable, can be increased compared to imposing only the mean WNG constraint. Second, we investigate the impact of array extension and microphone distribution on the VAH performance and show that for an array topology combining dense and sparse inter-microphone distances, the mean WNG and spectral distortion constraints can be satisfied for frequencies up to 8kHz without deteriorating the phase accuracy. Third, we investigate the performance of the VAH approach for dynamic auralizations with speech signals. Perceptual evaluations show that although individualization is an important capability of the VAH approach, the possibility of dynamic presentation is the main advantage of a VAH over conventional artificial heads.