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- presented by Prof Trevor Cox

Room dimensions for small listening rooms

The best room dimensions found

These web pages gives some more detailed numerical results from an Audio Engineering Society journal paper which appeared in June 2004. The journal paper gives more details of the method used and can be downloaded from the AES web site.

Map of room quality verses room ratios

 

For any particular room volume, it is possible to plot the variation of room quality for bass frequencies with the room ratios [1]. The right figure shows such a plot. Light areas correspond to uneven frequency responses, dark areas correspond to the best room sizes. The main light diagonal line running from the bottom left to top right corresponds to rooms where two of the dimensions are similar, having a square floor plan, and therefore the distribution of the modes is uneven and the figure of merit poor.

Using this type of analysis, it can be shown that there are very few room ratios (about 20 clustered around 1:2.19:3) that can be applied to a range of room volumes (50 - 200 m3). This is because room ratios are generally not scaleable. The ratios robust to room size were:

1: 2.16 : 2.96
1: 2.16 : 2.97
1: 2.16 : 2.98
1: 2.17 : 2.96
1: 2.17 : 2.97
1: 2.17 : 2.98
1: 2.17 : 2.99
1: 2.18 : 2.97
1: 2.18 : 2.98
1: 2.18 : 2.99
1: 2.18 : 3
1: 2.19 : 2.99
1: 2.19 : 3
1: 2.19 : 3.01
1: 2.19 : 3.02
1: 2.2 : 3.01
1: 2.2 : 3.02
1: 2.2 : 3.03
1: 2.21 : 3.02
1: 2.21 : 3.03
1: 2.22 : 3.03
1: 2.22 : 3.04

It is also found that the ratios in the literature are generally found to be poor in this analysis because the ratios are not robust to constructional variations.

The attached spreadsheet gives a list of the best ratios for the three room sizes tested. The room sizes are shown in the worksheet tabs.

It might not be possible to use the best ratios in the above spreadsheet because of building constraints. Consequently, another spreadsheet (2MB unzipped, 300k zipped) gives the second best ratios (corresponding to reasonable rooms but not the best, shown light grey in the illustration).

The results are limited to cuboid rooms (rectangular rooms). If your room has slanted surfaces, it will still suffer from modes, but they won't be well predicted by the algorithm used. Analysis has shown that the algorithm can tolerate a deviation of about 0.6m from a purely cuboid room.

The data is provided as is, and the University accepts no liability for using this data.

First page: Why choose the right room size?

Previous: Methods for choosing correct dimensions

[1] R. Walker. Optimum Dimension Ratios for Small Rooms. Preprint 4191. 100th Convention of the AES. (5/1996).

Trevor Cox's research pages

Re-use of material permitted provided it is clearly labeled "(c) University of Salford, www.acoustics.salford.ac.uk"