Room Axial Mode Frequency Calculator

Method, formula and assumptions

For each room axis, frequency = mode order x sound speed / (2 x axis length). The spread compares the three axis frequencies at the same order; it is not the spacing of every room mode.

Input definitions and supported units

• Room length (m): Measured or assumed numerical value, from 0.1 to 100; must be positive.
• Room width (m): Measured or assumed numerical value, from 0.1 to 100; must be positive.
• Room height (m): Measured or assumed numerical value, from 0.1 to 100; must be positive.
• Assumed sound speed (m/s): Measured or assumed numerical value, from 100 to 500; must be positive.
• Axial mode order: Whole-number count, from 1 to 20; must be positive.

Worked example with answer

A 5 x 4 x 2.5 m room at an assumed 340 m/s and order 1 gives 34, 42.5 and 68 Hz. The axis spread is 34 Hz.

How to use the results

Close axis frequencies identify a possible resonance cluster to investigate with measurements. Change the order to inspect harmonics without confusing them with oblique or tangential modes.

Results retain full precision internally and display up to four decimal places. Very small nonzero results use scientific notation rather than appearing as zero. Check the labels before comparing values across units.

Limitations and references

Assumes a rigid rectangular enclosure. Open doors, wall losses, nonrectangular geometry and speaker/listener positions alter measured response. It does not predict acoustic treatment performance.

The method is a self-contained arithmetic, geometric or explicitly stated mathematical model. There are no imported tariffs, empirical presets or equipment specifications; measured values and allowances must come from your own process.

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