Binaural technology for virtual reality

Abstract

The use of nonintrusive virtual environments is gaining more and more importance but was focused mainly on addressing the visual sense. However, the human perception consists not only of visual input and thus it would be worthwhile to create multimodal and interactive virtual environments. This thesis describes the techniques required to include the acoustic component into virtual environments and the implementation of a software system, which creates complex artificial acoustical scenes in real time. The system is based on the binaural technology. It features spatially distributed sound sources, which are utilized to create an environment that is as authentic as possible. This comprises a description of the source, including its relevant angle-, distance-, and time-dependent radiation, the sound distribution in the virtual scene, the perception-related consideration of all sound field components, and the exact reproduction at the ears of the user. In this context, an approach for dynamic crosstalk cancellation is presented, which enables a loudspeaker-based reproduction. The required filters are processed in real time on the basis of the position data and measured transfer functions of the outer ear. Furthermore the integration of this spatial audio system into a five-sided Virtual Reality display system is described and evaluated.

Intentional Switching in Auditory Selective Attention: Exploring Different Binaural Reproduction Methods in an Anechoic Chamber

“…First introduced by Atal and Schröder [38], CTC makes it possible to present binaural stimuli via loudspeakers. Detailed information about the theory and procedure can be found in Møller [39], Schmitz [40], and Lentz [41].…”

“…The used HRTFs were those of the artificial head described in reproduction method III. Since the subject'sm ovements were restricted to ±1cmi nt ranslation and ±2 • in rotation, the subject wasalways within the sweet spot [41].…”

Localization Performance in a Binaural Real-Time Auralization System Extended to Research Hearing Aids

“…Participants' head movements were constrained using a headrest, resulting in average front-back and back-front confusion rates of 13.4% and 15.7%, respectively. Lentz (2008), however, stressed the importance of dynamic aspects and reported a substantial reduction of reversals in the interactive binaural auralization systems compared to the static variants. This notion was corroborated by perceptual experiments where VSSs were synthesized based on a two-loudspeaker CTC system playing back pulsed pink noise stimuli with 200 ms duration and successive 500 ms silence interval.…”

Efficient range extrapolation of head-related impulse responses by wave field synthesis techniques

“…It is generally assumed that further increasing the distance does not change the characteristics of the HRIRs essentially [1]. However, it is known that HRIRs change signi cantly for nearby sources [2]. Such HRIRs are typically termed as near-eld HRIRs.…”