Reverberation Time Calculator

Reverberation time (T60) is the time for sound to decay by 60 dB after the source stops. It determines how a room sounds. Concert halls need ~2 s; recording studios ~0.3 s.

🔊 Acoustics📐 T60 = 0.161V/A🎵 Room Acoustics
Room Volume V (m³)
Total Absorption A (m²)
Please enter valid values.

Formula & Reference

VariableSymbolFormulaUnits
Reverberation TimeT60T60 = 0.161V/As
Room VolumeVV = length × width × heightm³
Total AbsorptionAA = ∑(αiSi)m² (sabins)
Absorption Coeffα0 = perfect reflection, 1 = perfect absorption—

Step-by-Step Examples

Example 1
Small Meeting Room

V=80 m^3, A=30 m^2 (carpet, acoustic tiles).

  • T60 = 0.161 * 80 / 30 = 0.43 s
✓ 0.43 s — good for speech, slightly dry
Example 2
Concert Hall

V=15000 m^3, A=3000 m^2 (audience, seats).

  • T60 = 0.161 * 15000 / 3000 = 0.805 s
  • Full audience needed for 1.8-2.0 s target
✓ 0.8 s with partial absorption — need lower A for fuller sound
Example 3
Recording Studio

V=100 m^3, A=80 m^2 (heavy acoustic treatment).

  • T60 = 0.161 * 100 / 80 = 0.20 s
✓ 0.2 s — very dry, ideal for recording

Real-World Applications

🎵
Concert Hall Design
Target T60 of 1.8-2.2 s for orchestral music, achieved by volume and absorption balance.
📖
Classroom Acoustics
T60 under 0.6 s recommended for speech intelligibility in classrooms.
🎤
Recording Studios
Very low T60 (0.2-0.4 s) with diffusers gives controlled acoustic environment.
⛪
Cathedral Acoustics
Cathedrals have T60 of 5-10 s, creating the long reverberant tail heard in organ music.

Common Mistakes to Avoid

⚠️
Sabine formula limitations

Sabine formula overestimates T60 for highly absorptive rooms (A > V). Use Eyring formula for absorption > 0.3.

⚠️
Absorption units (sabins)

Absorption A = alpha * S (absorption coefficient times surface area). A in metric sabins (m^2).

⚠️
Audience absorption varies

People absorb sound (alpha ~0.5). An empty concert hall has longer T60 than when filled with audience.

Frequently Asked Questions

What is the Sabine formula? ▾
T60 = 0.161*V/A, derived by Wallace Sabine in 1900. First quantitative acoustic formula, enabling modern room acoustic design.
What absorption coefficient means? ▾
Alpha = 0: perfect reflector (concrete). Alpha = 1: perfect absorber (open window). Most materials 0.1-0.8.
What is the ideal T60 for different rooms? ▾
Speech (classrooms): 0.4-0.6 s. Multi-purpose halls: 0.8-1.2 s. Concert halls: 1.8-2.2 s. Cathedrals/churches: 2-8 s.
What is the Eyring formula? ▾
More accurate for absorptive rooms: T60 = -0.161*V/(S*ln(1-alpha_avg)). Reduces to Sabine for low absorption.
How does furniture affect reverberation? ▾
Upholstered seats and furniture have high absorption (alpha ~0.5-0.7). Adding carpet and curtains significantly reduces T60.

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Formula Explorer connections

Interpretation: This relationship connects frequency, wavelength, speed, phase, intensity or resonance in an oscillating system. Assumption: Identify the medium, boundary conditions and reference frame. Linear waves, small amplitudes, nondispersive media or ideal resonance may be assumed.

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