Simple Explanation

Natural resonances in a room that cause some spots to sound louder or quieter.

Concise Technical Definition

Acoustic standing waves formed between room surfaces due to dimensional resonances, typically at frequencies where wall spacing equals half the sound wavelength.

Layman-Friendly Analogy

Like ripples bouncing between the sides of a bathtub—some spots get big waves, others stay still.

Industry Usage Summary

Room modes are critical in room acoustics and are managed with treatment or design to reduce uneven sound distribution.

Engineering Shortcut

Fundamental mode: f = c / 2L, where c is the speed of sound and L is the room dimension; higher modes are harmonics.

Full Technical Explanation

Eigentones or room modes are the natural resonant frequencies of an enclosed space, created when sound waves reflect between parallel surfaces and interfere constructively and destructively. This forms standing waves that cause uneven sound pressure levels—boosting or canceling frequencies depending on listener location. The primary mode occurs when the wavelength is twice the room dimension; harmonics occur at integer multiples. These modes can significantly affect audio quality, especially in small rooms, requiring acoustic treatments like bass traps or diffusers to mitigate their effects.