3D Audio



Introduction to Head-Related Transfer Functions (HRTF's): Representations of HRTF's in Time, Frequency, and Space
Abstract: This tutorial provides an introduction to Head-Related Transfer Functions (HRTF's) and their role in the synthesis of spatial sound over headphones. We define HRTF’s and discuss how they provide spectral cues which reduce the ambiguity with which the classical duplex theory decodes a free-field sound’s spatial location. We describe how HRTF’s are measured and how they are typically used to synthesize spatialized sound. By comparing and contrasting representations of HRTF’s in the time, frequency, and spatial domains, we highlight different analytic and signal processing techniques that have been used to investigate the structure of HRTF’s.

Distance Modelling
Abstract: Although the majority of research on spatial sound reproduction has concentrated on the directional components of source location, it is clear that full 3-dimensional rendering also requires an understanding of how to reproduce sound source distance. This article reviews and describes recent psychophysical research on distance perception of sound sources, with emphasis on how various acoustical and nonacoustical factors contribute to perceived distance. Results from this research have important implications for distance simulation and reproduction in spatial auditory displays.

LOCALIZATION OF A MOVING VIRTUAL SOUND SOURCE IN A VIRTUAL ROOM, THE EFFECT OF A DISTRACTING AUDITORY STIMULUS
Abstract: An audio localization test of moving virtual sound sources was carried out in a spatially immersive virtual environment, using loudspeaker array with vector based amplitude panning for reproduction of sound sources. Azimuth and elevation error in localization was measured. In this experiment the main emphasis was to explore the effect of a distracting auditory stimulus. Eight subjects accomplished a set of localization tasks. In these tasks they perceived the azimuth more accurately than the elevation. The distracting auditory stimulus decreased the localization accuracy. There was large variation between the subjects. The median error in azimuth for the most inaccurate subject was approximately twice as much as for the most accurate subject. The amount of the localization blur was dependent on angular distance from virtual sound source position to the nearest loudspeaker. The localization blur increased while the angular distance increased. Results of this experiment were compared with the results achieved in our previous experiment without the distracting stimulus.

A 3D sound primer by Gary Kendall
Abstract: The Goal of This Article As the technology for 3-D sound grows, there is a need to summarize and re-explain the field. The goal of this paper is to provide a primer on 3-D sound technology for people in the professional community who find it an increasingly important part of their fundamental knowledge and for the upcoming young professionals who need a starting point in their own learning process



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