Acouso Playground
Free room acoustics tool
Free reverberation time calculator
Estimate RT60 across six octave bands using Sabine or Norris–Eyring. Build a simple room, assign editable finishes, add acoustic treatment, and compare the response immediately.
Room editor
Assign finishes and treatments by surface
Everything you create stays in this browser tab for this visit only. Leaving the page or resetting restores the starting room.
Materials
Select a material, then choose Apply on a surface. You can also drag the card onto it.
Room surfaces
Each surface has one finish and up to one treatment. You'll confirm the treatment area before it is applied.Choose finishes and treatments in each surface card. Use Manage materials to view, edit, or create presets.
SurfaceAreaFinishTreatmentAction
48.0 m²Smooth gypsum or lime plaster
None
48.0 m²
No acoustic treatment applied.
24.0 m²Gypsum board on studs
None
24.0 m²
No acoustic treatment applied.
18.0 m²Gypsum board on studs
None
18.0 m²
No acoustic treatment applied.
24.0 m²Gypsum board on studs
None
24.0 m²
No acoustic treatment applied.
18.0 m²Gypsum board on studs
None
18.0 m²
No acoustic treatment applied.
48.0 m²Heavy carpet on concrete
None
48.0 m²
No acoustic treatment applied.
Ready. Select or drag a material to assign it.
Live estimate
Room reverberation
0.6 s
Room view
Drag away from the dimension labels to orbit. Drag the L, W, or H label along its arrow to resize, or focus a label and use the arrow keys. Scroll to zoom; use Fit room after large geometry changes. Double-click a face or select a surface row above. Treatment coverage expands uniformly from the centre for illustration; the calculation uses area, not displayed placement.
- Room volume
- 144.0 m³
- Total surface area
- 180.0 m²
- Baseline
- 1.49 s
- With treatments
- 1.49 s
500 Hz–1 kHz mean
500 Hz–1 kHz mean
0.89 s above the indicative target.
RT60 by octave band
Indicative comparison using the 500 Hz and 1000 Hz octave-band mean. The reference is indicative only, not a compliance result.
Baseline finishesWith treatmentsIndicative target
Baseline1.49 s500 Hz–1 kHz mean
With treatments1.49 s500 Hz–1 kHz mean0.89 s above the indicative target.
With treatments by octave band
1250.89 s
2501.93 s
5001.95 s
1k1.03 s
2k0.63 s
4k0.56 s
0.6 s indicative target
Take room analysis into Revit
Acouso-ROOM connects acoustic materials and results to rooms in your live project model.
How it works
A quick estimate built from room surfaces
RT60 describes how long sound takes to decay by 60 dB after a source stops. The calculator combines room volume with the area and frequency-dependent absorption of the floor, ceiling, and four walls.
Sabine
Sabine uses the room volume, V, and total equivalent absorption area, A. It is a familiar early estimate and the default method in this calculator.
Norris–Eyring
Norris–Eyring uses total surface area, S, and the area-weighted average absorption coefficient, ᾱ. Its result increasingly differs from Sabine as average absorption rises.
Which method should I use?
Sabine is a useful familiar starting point, particularly where average room absorption is relatively low. Norris–Eyring accounts for the proportion of energy retained at each reflection and can be useful in more absorptive rooms. Neither method models where a sound source, receiver, or treatment sits, and neither is universally more accurate.
The calculation runs independently at 125, 250, 500, 1000, 2000, and 4000 Hz. Treatment replaces the underlying finish over its area rather than being counted twice.
Material and target references
Editable presets draw from the published Acoustical Surfaces coefficient table. Real products vary with construction, thickness, mounting, and test method.
The classroom reference uses the 0.6-second recommendation in the AAAC Guideline for Educational Facilities Acoustics V2.0 and the 500 Hz and 1000 Hz Tmf convention described by AS/NZS 2107-based education guidance, while the historical meeting-room and open-workspace references draw from legacy WELL v1 reverberation-time guidance. Education, dining, and music-room references also draw from Building Bulletin 93, the 0.8–1.2 second speech-focused prayer-room range is based on published prayer-room research, and the volume-dependent amplified-venue range is approximated from Figure VII.1 of the WHO and ITU safe-listening guidance. Targets remain indicative starting points rather than compliance results.
Go deeper
Learn the room-acoustic methods
The calculator gives a fast answer. These guides explain the decay, mathematics, assumptions, and more detailed modelling approaches behind it.
What is reverberation time and RT60?
Understand sound decay, frequency bands, estimated RT60, and how room measurements differ from calculations.
Read the guide →Sabine vs Norris–Eyring
Explore the mathematics, assumptions, and practical differences between the two statistical methods.
Read the guide →Statistical, ray, and wave methods
See how quick reverberation estimates compare with spatial ray tracing and wave-based room models.
Read the guide →Common questions
Reverberation calculator FAQ
What does RT60 mean?
RT60 is the time, in seconds, for sound energy in a room to decay by 60 decibels after the source stops. It varies with frequency, so this calculator reports six octave bands rather than one universal value.
Should I use Sabine or Norris–Eyring?
Sabine is a familiar starting point for rooms with relatively low average absorption. Norris–Eyring accounts for the finite proportion of energy lost at each reflection and often produces a shorter estimate as average absorption rises. Neither is universally more accurate because both assume a diffuse sound field and average the room surfaces.
Is this reverberation time calculator a measurement?
No. It is an early design estimate based on room dimensions and absorption coefficients. A measurement uses sound sources, microphones, positions, and an established procedure such as ISO 3382.
Does treatment placement affect the result?
The calculation uses treatment area and absorption coefficients, not the displayed treatment position. Placement can affect real reflections and sound distribution, which requires more detailed analysis or measurement.
Beyond a browser estimate
Keep acoustic analysis connected to the model
Acouso-ROOM connects room calculations, acoustic materials, and project geometry directly to your Revit workflow.