Towards a Full-Bandwidth Numerical Acoustic Model

Prediction models are at the heart of modern acoustic engineering and are used in a diverse range of applications from refining the acoustic design of classrooms and concert halls to predicting how noise exposure varies through an urban environment. They also allow Auralisation to be performed for buildings and spaces before they are built or long after they are lost. Current commercial room acoustic simulation software almost exclusively approximates the propagation of sound geometrically as rays or beams. These assumptions yield efficient algorithms, but the maximum accuracy they can achieve is limited by how well the geometric assumption represents sound propagation in a given space. This compromises their accuracy at low frequencies in particular. Methods that directly model wave effects are more accurate but they have a computational cost that scales with problem size and frequency, effectively limiting them to small or low frequency scenarios. This paper will report the results of ongoing research into a new algorithm which aims to be accurate and efficient for all frequencies; the name proposed for this is the “Wave Matching Method”. This builds on the Boundary Element Method with the premise that if an appropriate interpolation scheme is designed then the model will become ‘geometrically dominated’ at high frequencies. Other propagation modes may then be removed without significant error, yielding an algorithm which is accurate and efficient. This paper will present the general concepts of the algorithm and progress to date. PACS no. 43.20.Rz, 43.20.Fn