External websites we've worked on: Dr Andy Moorhouse on piano ... Prof Trevor Cox
Design and Application of Room Diffusers
Professor Cox has worked on developing diffusers both in research and commercially. For instance, Sony M1 is one of the most prestiguous post-production studios in the world where music by Davie Bowie, Paul McCartney and others have been mixed and mastered. Diffusers are used to remove acoustic problems in rooms such as colouration and echoes. A few years ago, Trevor completed an overview paper on diffusers aimed at a non-acoustic audience for Interdisciplinary Science Reviews. You can read a copy of the paper here (c) 2003 IoM Communications Ltd, not to be reproduced without permission. This gives an overview of what diffusers are used for and why.
In diffuser design you are trying to disperse reflections both spatially and temporally, as the above linked article discusses. Below are some VRML images of polar responses. To view and spin these, you will need a VRML plug in. Trevor uses the (free) Cortona VRML Client and there are plenty of others. Click on the thumbnail to activate the VRML image, use the back button on the browser when you have finished.
This is scattering from a plane surface. The energy is directed in one direction (vertically), the specular reflection direction.
This is scattering from a periodic set of arcs. The energy is directed into a number of directions due to grating lobes. The specular lobe is straight up, and the four first order lobes are quite clearly shown nearby.
This is scattering from a designed diffuser. The energy is directed more evenly than the previous surfaces. The surface is actually rather shallow compared to wavelength at this frequency, and so the attenuation of the specular lobe is limited by the surface depth. No grating lobes are apparent because the diffuser is not in a periodic arrangement.
Some other projects I have worked on are linked below, they will take you to an external site.
Top developments of note
- Verification and development of prediction methods for diffusers, especially application of boundary element methods (BEMs).
- Developing optimisation methods to enable visual and acoustic requirements to be simultaneously considered.
- Developing diffusion coefficients to evaluate diffuse scattering, more here.
- First research text devoted to diffusers
Many more papers on diffusion can be found on my publications page