Prediction of acoustic response and speech intelligibility based on a hybrid ray tracing / SEA technique.

Prediction of acoustic pressure in open spaces such as vehicle exterior or of audio system sound quality or speech intelligibility inside cars, trains, aircraft, or buildings must consider inclusion of both direct sound field as well as reflected specular or diffuse field of the source for the analysis of frequency or time domain acoustic response. Numerical methods may handle different acoustic field. However; these methods may need a lot of resources to simulate big models and large acoustic enclosures at high frequencies. Statistical Energy Analysis (SEA) model has much of the required information about the geometry and materials required to make this prediction low resource requirements. However, the SEA model is limited to prediction of the steady-state reverberant sound field and does not have the information necessary to predict the time-domain direct-field signal from the source. In this paper, two ray-tracing based method are presented. For exterior spaces, a sound propagation technique is presented to compute the total field from the source to the receivers. The total field is represented as the sum of direct, reflected and diffracted field. For interior spaces and prediction of speech intelligibility, an efficient hybrid acoustic Ray-tracing/SEA model is used where the early reflections are model with raytracing and the late reflections are modeled with a statistical approach. In this model, both the boundary and air absorption effects are considered. The accuracy of the proposed technique in the prediction of both acoustic response and speech intelligibility are evaluated against numerical and experimental results.