Room Mode Calculator

About this calculator

An axial room mode is a standing wave that forms between two parallel, opposite surfaces — say the front and back walls — when a sound wave’s reflection reinforces itself at specific frequencies. The first axial mode along any dimension is f = c / (2 × L), with higher modes at 2f, 3f and so on, where c is the speed of sound (343 m/s) and L is the room length, width, or height in metres.

Because a rectangular room has three axial dimensions, it produces three families of resonances that boost bass at some frequencies and cancel it at others, creating the uneven low-end response and “boomy corners” familiar in small rooms. Acousticians, recording-studio designers and home-theater installers calculate these modes to place speakers and listening positions away from nulls, choose bass-trap locations, and judge whether a room’s proportions will cause modal clustering.