Eyring & Fitzroy Reverb Time Calculator
Architectural acoustics: Compute reverberation time ($T_{60}$) in dead rooms and spaces with non-uniform absorption using the Norris-Eyring and Fitzroy formulations.
Room Enclosure Dimensions
Directional Absorption Coefficients (α)
Front/rear walls (2 × W × H)
Lateral walls (2 × L × H)
Acoustic ceiling/carpet (2 × L × W)
Why Sabine Fails in Treated Rooms
Sabine's formula $T_{60} = 0.161 V / A$ erroneously predicts $T_{60} > 0$ even if all surfaces are 100% absorbing ($alpha = 1.0$). Norris-Eyring corrects this using $-ln(1 - ar{alpha})$. Fitzroy further corrects for non-uniform spatial absorption (e.g. heavily treated ceilings with reflective bare walls).
Reverberation Time Predictions (RT₆₀)
Norris-Eyring T₆₀
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Fitzroy Non-Uniform T₆₀
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Classical Sabine T₆₀ (For Comparison)
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Surface & Absorption Balance
Average Absorption Coefficient (ᾱ):
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Total Boundary Surface Area (S):
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Total Absorption (Metric Sabins):
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Acoustic Flutter / Non-Uniformity:
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