Room acoustics and sound
Decibel addition and background correction, inverse-square distance loss, room modes with a chart, RT60 by Sabine and Eyring from a materials table, speed of sound and wavelength, note ↔ frequency with adjustable A4, and a tone, noise, and sweep generator.
Added
How to use it
-
Decibels — incoherent levels add as 10·log₁₀ Σ10L/10 (two equal sources = +3 dB). Distance: −20·log₁₀(r₂/r₁) from a point source (−6 dB per doubling), −10·log₁₀ from a line source. SPL from sound power: Lp = LW + 10·log₁₀(Q/4πr²).
-
Room modes — for a rectangular room, f = (c/2)·√((nx/L)² + (ny/W)² + (nz/H)²). Axial modes (one non-zero index) are strongest; clusters of them make boomy notes and wide gaps make dead spots. Each mode is shown with its nearest note.
-
RT60 — Sabine T = 0.161·V/A and Eyring T = 0.161·V/(−S·ln(1 − ᾱ)), per octave band from 125 Hz to 4 kHz. Choose finishes for walls, floor, and ceiling, then add patches (windows, panels, curtains) that replace wall area. Absorption coefficients are typical published values. The Schroeder frequency marks where modes give way to statistical reverberation.
-
Speed and notes — c = 331.3·√(1 + T/273.15) m/s in dry air; equal temperament f = A4·2^(n − 69)/12^.
-
Tone generator — sine, square, sawtooth, or triangle on a log-scaled slider, white/pink/brown noise, and logarithmic sweeps, all generated with the Web Audio API in your browser. Start quietly.
| For learning and planning. Measure real rooms; these are idealised (rigid-walled, diffuse-field) models. |
Feedback is a gift. Something to improve, a feature to add, or a bug? Tell me.
Runs entirely in your browser; nothing you type leaves this page.