Enrichment · Passion Projects · Audio and broadcast

How long does
your room ring?

List the room’s size and its surfaces. The calculator works out the reverberation time by Sabine’s formula, compares it with a goal for recording or teaching, and tells you how much panel to add before you buy any.

Measure the echoWhat you get

The room acoustics calculator

The worked example is a carpeted spare bedroom with a few panels behind the microphone. Nothing you type leaves this browser.

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What you get

Enrichment · Passion ProjectsFree

What you finish with
Volume, total absorption, the reverberation time, the gap to your goal, the panel area to add and each surface’s share. It prints as a summary and downloads as a spreadsheet.
Who it is for
Students recording podcasts, music or video, audio production teachers, and families setting up a quiet room.
Format
Browser calculator for a phone, tablet or computer, by touch or keyboard. Prints a summary; downloads a spreadsheet (.csv); export and import a file.
Access
Free. No account, no sign-in and nothing to install. Everything you type stays in this browser; nothing is sent to Caveat.
Where it lives
The Passion Projects space in Caveat Enrichment.
Support
Questions, a correction or a request: team@caveatacademic.com.

How to use it

  1. Measure the room inside and choose feet or metres.
  2. List the floor, the ceiling, the walls, windows and any panels, with areas.
  3. Pick the finish closest to each surface.
  4. Choose the goal for how the room will be used.
  5. Read the time and the panel area to add.

Measure the echo

How the reverberation time is worked out

Sabine’s formula: volume over absorption.

The worked example: a spare bedroom used for a podcastVolume960 cu ft12 × 10 × 8 ftAbsorption55.1 sabinsarea × coefficient, summedRT600.85 s0.049 × 960 ÷ 55.1Panel to add120 sq ftto reach 0.3 sThe worked example: a spare bedroom used for a podcastVolume960 cu ft12 × 10 × 8 ftAbsorption55.1 sabinsarea × coefficient, summedRT600.85 s0.049 × 960 ÷ 55.1Panel to add120 sq ftto reach 0.3 s
Bigger rooms ring longer; every square foot of soft surface shortens the ring.

Sabine’s formula

Wallace Sabine found in the 1890s that the time for sound to fade by 60 decibels is proportional to a room’s volume and inversely proportional to its absorption. Each surface absorbs its area times a coefficient between 0, a perfect mirror, and 1, an open window. Add them up and divide.

Reading the result

Speech recorded in a room above about half a second sounds roomy; voice booths aim near 0.3 seconds. Classrooms under 10,000 cubic feet should be at or under 0.6 seconds under ANSI/ASA S12.60. Thin foam soaks up high pitches only, so small rooms often still boom; thick panels and corner bass traps reach lower.

Sources

  1. Acoustical Society of America. ANSI/ASA S12.60, Acoustical Performance Criteria, Design Requirements and Guidelines for Schools (acousticalsociety.org).
  2. Sabine, W. C. (1922). Collected Papers on Acoustics. Harvard University Press.
  3. Long, M. (2014). Architectural Acoustics (2nd ed.). Academic Press. Absorption coefficient tables.
  4. U.S. Access Board. Classroom acoustics guidance (access-board.gov).

The worked example is made up. Coefficients are typical values; your panels’ data sheet is the better source. Your entries stay in this browser. Support: team@caveatacademic.com.