What causes standing waves in a room?

Standing waves occur when sound reflects between parallel surfaces and the reflected wave reinforces the original. This happens when the distance between surfaces is a whole number multiple of half the wavelength. The result is areas of high and low pressure (nodes and antinodes) at fixed positions in the room.

How do I reduce standing wave problems?

Bass traps in room corners are the most effective treatment. Corner-mounted traps work on modes in all three axes. Membrane absorbers and Helmholtz resonators can target specific problematic frequencies. Moving the listening position away from walls and room centre also helps.

What are axial, tangential and oblique modes?

Axial modes occur between two parallel surfaces and are the strongest. Tangential modes involve four surfaces and are about 3 dB weaker. Oblique modes involve all six surfaces and are about 6 dB weaker. This calculator shows axial modes only, as they are the most problematic.

AudioCalcs

Standing Wave Calculator — Room Modes

Find standing wave frequencies and axial room modes for rectangular rooms.

Length

Width

Height

How We Calculate This

f = n × v / (2 × L)

Where n is the mode number (1, 2, 3...), v is 343 m/s (speed of sound at 20°C), and L is the distance between parallel surfaces. Mode 1 has a half-wavelength fitting between the surfaces, mode 2 has a full wavelength, and so on.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates based on standard formulas. Always verify results for critical applications.