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Sound Absorption & Sabine Reverberation Time (RT60) Calculator

Formulated by Wallace Clement Sabine in the late 1890s at Harvard, RT60 defines the time required for acoustic sound energy to decay by 60 decibels after the sound source stops.

Enclosed three-dimensional room volume in cubic meters.

Sum of all ceiling, wall, and floor interior surface areas.

Area-weighted sound absorption coefficient (Glass/Concrete ≈ 0.05, Drywall/Carpet ≈ 0.15 - 0.25, Acoustic Foam ≈ 0.60 - 0.90).

Calculated Result
0.95 s

Reverberation Time (RT60)

Reverberation Time (RT60)

0.95 seconds

Acoustic Environment Classification

Ideal for Chamber Music & Multipurpose Auditoriums

Total Metric Absorption (A)

85 Sabins (m²)

Room Dimensions

Volume: 500 m³ | Surface: 450 m²

Mean Absorption Coefficient (ᾱ)

0.18

Calculation Breakdown

  1. 1. Calculate Total Sound Absorption (Metric Sabins)A = S · ᾱ + 4·m·V = (450 m² · 0.18) + (4 · 0.002 · 500) = 85 metric Sabins
  2. 2. Sabine Equation for RT60RT60 = 0.161 · V / A = 0.161 · 500 m³ / 85 = 0.95 seconds
  3. 3. Acoustic SuitabilityAt 0.95s, the space is classified as: Ideal for Chamber Music & Multipurpose Auditoriums.

RT60 vs Mean Absorption Coefficient (500 m³ Room)

Interactive visualization based on your current inputs

RT60 (s)
0.00.81.52.33.00.05 (Concrete)0.10 (Plaster)0.18 (Current)0.30 (Treated)0.50 (Studio)Absorption ᾱRT60 (seconds)

What Is the Sound Absorption & Sabine Reverberation Time (RT60) Calculator?

RT60 is the canonical metric in architectural acoustics measuring the persistence of sound in an enclosed space after the original sound ceases.

How Does the Sound Absorption & Sabine Reverberation Time (RT60) Calculator Work?

Sound bounces repeatedly off boundaries; each reflection absorbs energy proportional to material acoustic absorption coefficients.

Sound Absorption & Sabine Reverberation Time (RT60) Calculator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

A = \sum (S_i \cdot \alpha_i) + 4 m V, \quad RT_{60} = \frac{0.161 \cdot V}{A}

Total absorption A in metric Sabins is surface area times mean absorption coefficient. Reverberation time RT60 equals 0.161 times room volume over total absorption.

How to Use the Sound Absorption & Sabine Reverberation Time (RT60) Calculator

  1. Enter total room volume in cubic meters.
  2. Specify combined surface area of boundaries.
  3. Input the area-weighted average absorption coefficient ᾱ.

Step-by-Step Example Calculation

500 m³ Lecture Hall with Carpet and Acoustic Ceiling (ᾱ = 0.18)

Input Values:

roomVolumeM3:500
totalSurfaceAreaM2:450
averageAbsorptionCoefficientAlpha:0.18
Worked Steps: Total room absorption is 85.0 metric Sabins, yielding an RT60 of 0.95 seconds—ideal for clear lecture and speech intelligibility.

Understanding Your Result

RT60 (seconds): Decay time for 60 dB sound drop.

Total Absorption (Sabins): Acoustic sponge capacity of the room.

Acoustic Classification: Suitability for speech vs symphonic performance.

Factors That Affect the Result

  • Large volume increases RT60; soft porous absorptive surfaces decrease RT60.

When Should You Use This Calculator?

  • Recording studio treatment, classroom acoustic compliance, cinema auditorium design, and house of worship sound engineering.

Assumptions & Limitations

  • Sabine’s formula assumes a diffuse sound field with evenly distributed absorption. Rooms with high absorption (ᾱ > 0.35) are better evaluated using Eyring’s formula.

Frequently Asked Questions

Calculation Accuracy & Reference Note

Standard classical Sabine architectural acoustics formulation.

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