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Room Mode Calculator

This calculator requires a JavaScript capable browser
English Units Version

This JavaScript calculator will determine the Axial, Tangential and Oblique room modes of regular rectangular shaped rooms with uniform wall construction. Axial room modes involve only a single room dimension, Tangential room modes involve two surfaces and Oblique modes involve three surfaces (across the corners). This is especially useful in finding the optimum room shape for home theatre and listening rooms, studios, and practice rooms. When the modal frequencies are plotted on a graph (still just a bit beyond the capability of JavaScript) the distribution should be uniform, and there should not be a stacking of modal frequencies. For all practical purposes, any modal frequencies above 300Hz will be swamped by other room acoustic effects.

This Javascript calculator only looks at the first 9 integer values for each type of mode (1-1-1, 2-2-2, 3-3-3, ...9-9-9) and does not necessarily capture every possible mode. It's primary purpose is to show the basic effects of inappropriate room dimension selections and not act as a design tool. If you need a design tool, you may want to investigate RPG Room Optimizer software

Room Dimensions

Room length
Metres

Room width
Metres

Room height
Metres


Axial Room Modes

Axial room modes
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Tangential Room Modes

Tangential room modes have 1/2 of the energy of axial modes (-3dB). This calculator only plots tangential modes of the same order for each reflection in each plane (eg: 1,1,0: 1,0,1: 0,1,1: 2,2,0: 2,0,2: 0,2,2 etc.) which will not cover all possible modes. This is strictly a limitation in the file size of the javascript calculator and output plotting ability. If you want to find every possible mode, you'd need to take a more rigorous approach.

Tangential Room modes
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Oblique Room Modes

Oblique room modes have 1/4 of the energy of axial modes (-6dB). This calculator only plots oblique modes of the same order for each reflection in each configuration (eg: 1,1,1: 2,2,2: 3,3,3: 4,4,4 etc.) which will not cover all possible modes like 1,2,1 or 2,3,4 etc.. This is strictly a limitation in the file size of the javascript calculator and output plotting ability. If you want to find every possible mode, you'd need to take a more rigorous approach.

Oblique room modes
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Images from B&K Technical Review.

This information is provided with no warranty of its accuracy, or applicability, and any use made of this information is done so at the sole risk of the user.

amazon-logo.gif - 1678 Bytes Visit our reference book page for a list of recommended reading on acoustics, sound systems, loudspeakers, studio technique and construction, educational multimedia, home theatre, live theatre sound, control system programming and other relevant technical topics.
Mc Squared System Design Group, Inc Mc Squared System Design Group, Inc
323 - 901 West 3rd Street
North Vancouver, BC V7P 3P9
Phone 604 - 986 - 8181
FAX (604) - 988 - 9751