Helsinki Visit

Although research at both York and Aalto encompasses standard room acoustics simulation methods based on geometric acoustic techniques (where sound is assumed to behave as a ray of light with the associated limitations involved with making such an assumption) most of our interests and efforts are focused on approaches that solve the acoustic wave equation directly, that therefore offer the potential for a full, complete and accurate simulation of the soundfield within an enclosed space.

The aim of this visit was to facilitate a benchmark study in the use and testing of new room acoustic prediction and auralisation methods for a number of specific ideal and real-world scenarios. This resulted in the following objectives:

(1) Consolidation of code into an appropriate framework for carrying out this benchmark study.

Finite Difference Time Domain (FDTD) wave simulation work was carried out in prototype Matlab code and using the Aalto developed WaveModeller software that integrates with Google Sketchup for 3D Design and includes GPU acceleration based on the NVIDIA CUDA library. Work is ongoing to develop an optimal modular design and simulation strategy suitable for wider distribution and use within the community.

(2) design, carry out and write up testing of new room acoustic prediction and auralisation methods;

Three papers have been completed and are in various stages of publication. The first presents a generic framework for higher order ambisonic encoding of FDTD models based on a circular array of omnidirectional receivers, and is demonstrated to give good objective and subjective results (published). The second paper explores source excitation strategies for FDTD room acoustic modeling (revised after first round of reviews). The third paper is the first to offer a more complete testing of a hybrid room acoustics algorithm, based on analytical testing, use of established metrics and real-world simulation scenarios (submitted).

(3) organise and present results at the first York-Aalto Auralisation Workshop.

19 researchers, including 7 from York, 1 representative from industry, and 11 from Aalto University participated in two days of presentations, exchanges and demonstrations. A summary is available at the given link. This has helped to consolidate our research relationship and will encourage future sharing of results and interactions. Prof. Savioja will be delivering an invited workshop on using GPUs for audio processing at the forthcoming 15th International Conference on Digital Audio Effects to be held in York in September 2012.