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Reverberation Time (Sabine's Formula) Calculator

Estimates the time required for sound to decay by 60 decibels (RT60).

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RT60

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Overview

Sabine's Formula is the foundational equation in architectural acoustics used to determine the time required for sound to decay by 60 decibels. It establishes a quantitative relationship between a room's physical volume and the total acoustic absorption provided by its surfaces and contents.

Symbols

Variables

= RT60, V = Volume, A = Absorption

RT60
Volume
Absorption
sabins

Apply it well

When To Use

When to use: Use this formula when designing large, reverberant spaces like auditoriums or concert halls where the sound field is diffuse. It is most effective when the average absorption coefficient of the room is relatively low (below 0.2).

Why it matters: This equation allows designers to calculate the exact amount of acoustic treatment needed to ensure speech intelligibility or musical clarity. It prevents rooms from being too 'echoey' for communication or too 'dead' for performance.

Avoid these traps

Common Mistakes

  • Using incorrect units for volume or area.
  • Convert units and scales before substituting, especially when the inputs mix s, , sabins.
  • Interpret the answer with its unit and context; a percentage, rate, ratio, and physical quantity do not mean the same thing.

One free problem

Practice Problem

A recording studio control room has a volume of 150 m³ and a total calculated absorption of 30 Sabins. Calculate the RT60 reverberation time for this space.

Volume150 m^3
Absorption30 sabins

Solve for: RT60

Hint: Divide the volume by the total absorption before multiplying by the Sabine constant of 0.161.

The full worked solution stays in the interactive walkthrough.

References

Sources

  1. Architectural Acoustics by M. David Egan
  2. Fundamentals of Acoustics by Lawrence E. Kinsler, Austin R. Frey, Alan B. Coppens, James V. Sanders
  3. Wikipedia: Reverberation
  4. Everest, F. Alton, and Pohlmann, Ken C. Master Handbook of Acoustics. 5th ed., McGraw-Hill Education, 2009.
  5. Egan, M. David. Architectural Acoustics. J. Ross Publishing, 2007.
  6. Wikipedia: Reverberation (specifically the section on Sabine's formula and its constants for different unit systems).
  7. M. David Egan, Architectural Acoustics
  8. Lawrence E. Kinsler, Austin R. Frey, Alan B. Coppens, James V. Sanders, Fundamentals of Acoustics