The advent of computer simulation and visualisation techniques for acoustic design and analysis has made predictions much more accurate and the results spectacular. Advanced modelling of room acoustics is done through production of a 3D CATT (Computer Aided Theatre Technique) model, application of material acoustic properties to all surfaces and a ray tracing algorithm. At low frequencies, sound has to be considered as a spherically propagating wave which is incredibly computationally intensive. At mid-high frequencies, sound can be considered as a ray, similar to a beam of light. This is where the possibilities of acoustics modelling are realised.
Depending on where sound sources (singers, loudspeakers, etc.) and receivers (audience, microphones etc.) in the room are anticipated, virtual sound rays are sent out in all directions, bouncing off every surface. The signal at virtual microphones within the model are used to extract the acoustic “signature” of the space and determine its quality.
The range of parameters considered to contribute to excellent acoustics in auditoria is large. Consideration must be taken for Reverberation Time, Early Decay Time, Early to Late Energy Ratio, Clarity, Lateral Energy Fraction, Source Strength (G) and Speech Intelligibility.
The balancing of these parameters is a subtle process and is based on experience of listening to and measuring completed auditoria. Each hall will have a slightly different “signature”.
Here at Gillieron Scott Acoustic Design we have modelled over 50 auditoria including
- The Bridge Theatre in London
- The Everyman Theatre in Liverpool
- The Roundhouse in London
- The Olympic 2012 Velodrome
- The Saffron Hall in Saffron Walden
- Nazrin Shah in Worcester College (Oxford)
- Jesus College in Cambridge
- Wells Cathedral School in Wells and many more.
The results obtained during commissioning have been very encouraging showing an accurate correlation between prediction and actual results.