Room Acoustics Forum by Rives Audio

RE: optimum room dimension ratios

83.84.178.82

In Reply to: RE: New room questions regarding shape & trapping posted by Andrew_P on May 31, 2008 at 10:07:55

Room mode formulas and also formulas for determining optimum dimension ratios are based on the assumption that 1. the room is empty, 2. all boundaries are perfectly reflective, 3. there are no openings such as doors and windows.

Furthermore, the only scenario for which optimized ratios make sense is sound source and listening position in opposite corners. Optimizing prodedures attempt to spread the room mode frequencies, ALL mode frequencies, evenly or harmonically or whatever on the frequency scale. The only place where you excite ALL room modes fully is in a corner, the only place where you perceive maximum amplitude of ALL modes is in a corner. Everywhere else you will not excite all modes fully but only proportionally, depending on the position of the source in the room.

Further, in order to excite all modes simultaneously you need program material that contains all mode frequencies at a given moment, if not, only a fraction of the modes will be excited.

Further, it has been shown that there is no link between dimension ratios and perceived sound quality:

Fazenda et al. (2005), “Perception of modal distribution metrics in critical listening spaces - Dependence on room aspect ratios”, J. of Audio Eng. Soc., p.1128

The concept of optimum dimension ratios stems from reverberation chambers where acoustic measurements are made. If you measure the sound field around broadband sound sources such as machinery, cars, whatever, you will have microphones all over the place and in such case evenly spread mode frequencies make sense.

So, in conclusion, forget about optimzed dimension ratios, chose whatever dimensions suit you best in terms of feasability and costs.

Klaus

Follow Ups:

RE: optimum room dimension ratios - David Aiken 14:48:42 05/31/08 (1)
- RE: It does not matter where your speakers are located. - KlausR. 21:24:08 05/31/08 (0)

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