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Title: Ambisonics and higher-order ambisonics for off-centre listeners : evaluation of perceived and predicted image direction
Author: Stitt, Peter
ISNI:       0000 0004 5368 5568
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2015
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Higher Order Ambisonics is a spatial audio technique that aims to recreate a sound image over as large a listening area as possible. Only limited investigation has taken place into localisation with Ambisonics and Higher Order Ambisonics at off-centre listening positions. This thesis presents the results of three psychoacoustic localisation experiments Investigating off-centre localisation of first and third order Ambisonics under different conditions: for studio and concert hall sized arrays, and for transient vs ongoing stimuli. A detailed analysis of the results of each experiment is carried out 'to determine the robustness of the tested systems. Comparisons are made between the results of the three experiments to determine the influence of changing the stimulus or increasing the arrival time delay between loudspeakers, where the relative gains of the loudspeakers was found to be perceptually more important than increased time differences between them. The usefulness of these results can be increased by comparison with models for prediction of human localisation, where a robust model would afford fast evaluation of ambisonic systems and allow system optimisation for off-centre positions. Therefore, evaluation Is performed for two binaural models on their ability to predict the results of the psychoacoustic experiments. A model by Dietz and a modified version of the Undemann model are evaluated. Finally, the energy vector model, prevalent in the Ambisonics community, is extended to include elements of the precedence effect. The binaural models, the standard energy vector, and the precedence-extended model are evaluated by comparison to the perceptual results. The robustness of each of the binaural and vector models is discussed in the context of their use as predictors of localisation at off-centre listening positions. The predictions of the precedence~extended energy vector are found to exhibit the lowest deviation from the perceptual results.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available