Free Acoustic Resonance Calculator

Calculate the resonant frequencies of a rectangular room: f = (c/2) * sqrt((nx/Lx)^2 + (ny/Ly)^2 + (nz/Lz)^2).

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Resonant Frequency

21.4375 Hz

Resonant Frequency vs Room Length (Lx)

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Room Acoustic Modes

A rectangular room supports standing waves at specific resonant frequencies determined by its dimensions.

Formula

f(nx,ny,nz) = (c/2) sqrt((nx/Lx)^2 + (ny/Ly)^2 + (nz/Lz)^2)

  • *c* = 343 m/s (speed of sound in air)
  • *Lx, Ly, Lz* = room dimensions
  • *nx, ny, nz* = mode numbers (non-negative integers, not all zero)

    • Axial modes (one non-zero index) are strongest. Tangential (two) and oblique (three) modes are progressively weaker.

    Example Calculation

    Room 8 x 5 x 3 m, first axial mode along length (1,0,0).

    1. 01f = (343/2) * sqrt((1/8)^2 + 0 + 0)
    2. 02f = 171.5 * sqrt(0.015625)
    3. 03f = 171.5 * 0.125
    4. 04f = 21.44 Hz

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