PRISM – 3D Acoustic Model

 

Prism-RA – 3D Acoustic Model

PRISM-RA is a hybrid numerical and geometrical DSP, 3D acoustic model used to visualize and predict parameters used in room acoustics. There are two common methods used to predict parameters in room acoustics; empirical and geometrical.

Empirical methods

These methods are employed in simple spaces by acoustic consultants, architects and other professionals.  They can provide quick estimates for the reverberation time of a space.

Results obtained from empirical methods are limited in accuracy and are usually used in rooms with simple geometry.

Geometrical methods

These methods create sound ‘rays’ or ‘particles’, which are subject to the laws of reflection. Ray-tracing and image source models can often provide more accurate results. They are useful in rooms which have complex geometry or an uneven distribution of absorption.

The accuracy of the methods can however be called into question. The methods are known to provide less than accurate results when used in small rooms or when assessing low frequencies.

Wave effects such as diffusion are not accounted for, and often require work-arounds. This can lead to an uneven distribution of sound, which can show up as ‘quiet’ areas in noise maps.

Numerical methods

For years numerical calculations methods (FDTD, FEM, BEM, etc) have been used to solve big problems in physics. Some ares in of study are: Thermodynamics, Electromagnetics, Fluid Dynamics, and of course acoustics.

Numerical models solve partial differential equations, making them potentially very accurate. PRISM-RA uses the 3D FDTD method for its calculations and therefore has the potential to be one of the most accurate pieces of room acoustic software available.

The software is unique when compared to existing room acoustic software. New parallel processing techniques allow the software utilize hundreds of GPU cores available to most modern graphics cards.

 

This means that numerical calculations can be carried out in a reasonable amount of time, without the need for a super-computer!

For laptop computer users or those with an incompatible GPU, a hybrid model allows for the higher frequencies to be run as a geometrical model.

An algorithm is in development which will optimize the accuracy and time of calculations according to processing power.

 

 

 

Finally, the software is not currently available and is currently in the process of being re-written. There are however a number of big updates regarding PRISM-RA to come shortly (2018)!

 

For more information regarding the latest developments in 3D audio and virtual reality, see our post here.

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