Simulation and analysis of spatial audio reproduction and listening area effects

Loudspeaker-based spatial audio systems are often designed with the aim to create an auditory event or scene to a listener positioned in the optimal listening position. However, in real-world domestic listening environments, listeners can be distributed across the listening area. Any translational change from the central listening position will introduce artefacts which can be challenging to evaluate perceptually. Simulation of a loudspeaker system using non-individualised dynamic binaural synthesis is one solution to this problem. However, the validity in using such systems is not well proven.This thesis measures the limitations of using a non-individualised, dynamic binaural synthesis system to simulate the perception of loudspeaker-based panning methods across the listening area. The binaural simulation system was designed and verified in collaboration with BBC Research and Development. The equivalence of localisation errors caused by loudspeaker-based panning methods between in situ and binaural simulation was measured where it was found that localisation errors were equivalent to a +/-7 degrees boundary in 75% of the spatial audio reproduction systems tested. Results were then compared to a computation localisation model which was adapted to utilise head-rotations. The equivalence of human acuity to sound colouration between in situ and when using non-individualised binaural simulation was measured using colouration detection thresholds from five directions. It was shown that thresholds were equivalent within a +/-4dB equivalence boundary, supporting the use for simulating sound colourations caused by loudspeaker-based panning methods. The binaural system was finally applied to measure the perception of multi-loudspeaker induced colouration artefacts across the listening area. It was found that the central listening position had the lowest perceived colouration. It is also shown that the variation in perceived colouration across the listening area is larger for reverberant reproduction conditions

The influence of headphones on the localization of external loudspeaker sources

When validating systems that use headphones to synthesize virtual sound sources, a direct comparison between virtual and real sources is sometimes needed. This paper considers the passive influence of headphones on the sound transmission and perception of external loudspeaker sources, for which physical measurements and behavioral data have been obtained. Physical measurements of the effect of a number of headphone models are given and analyzed using an auditory filter bank and binaural cue extraction. These highlighted that all of the headphones had an effect on localization cues and repositioning had a measurable effect. A localization test was undertaken using one of the best performing headphones from the measurements. It was found that the presence of the headphones caused a small increase in localization error and that the process of judging source location was different, highlighting a possible increase in the complexity of the localization task

On the externalization of sound sources with headphones without reference to a real source

International audienc