This thesis investigates if reliability in objective acoustic metrics obtained for an auralized space implies accuracy and reliability in terms of the subjective listening experience. Auralizations can be created based either on impulse response measurements of an existing space, or simulations using computer-based acoustic models. Validations of these methods usually focus on the observation of standard objective acoustic measures and how these vary under certain conditions. However, for accurate and believable auralization, the subjective quality of the resulting virtual auditory environment should be considered as being at least as important, if not more so.
This study is focused in the most part on St. Margaret’s Church, York, UK. Impulse responses have been acquired in the actual space and virtual acoustic models created using CATT-Acoustic and ODEON-Auditorium auralization software, both based on geometric acoustic algorithms. Variations in objective acoustic parameters are examined by changing the physical characteristics of the space, the receiver position and the sound source orientation. It is hypothesised that the perceptual accuracy of the auralizations depends on optimising the model to minimise observed changes in objective acoustic parameters. This objective evaluation is used to ascertain the behaviour of certain standard acoustic parameters. From these results, impulse responses with suitable acoustic values are selected for subjective evaluation via listening tests.
These acoustic parameters, in combination with the physical factors that influence them, are examined, and the importance of variation in these values in relation to our perception of the result is investigated. Conclusions are drawn for both measurement and modelling approaches, demonstrating that model optimisation based on key acoustic parameters is not sufficient to guarantee perceptual accuracy as perceptual differences are still evident when only a simple acoustic parameter demonstrates a difference of greater than 1 JND. It is also essential to add that the overall perception of the changes in the acoustic parameters is independent of the auralization technique used. These results aim to give some confidence to acoustic designers working in architectural and archeoacoustic design in terms of how their models might be best created for optimal perceptual presentation.
