— RT60 Calculator - Auditorium & assembly
Bare auditorium shell, 1,296 m3, RT60 2.9 s
Problem. An 18 x 12 x 6 m assembly hall built as a bare hard shell - wood floor, drywall walls and drywall ceiling - needs checking before any acoustic treatment is specified. A hard shell tends to ring, and the design needs to know by how much and roughly how much absorber closes the gap.
Answer. With 1,296 m3 of volume, only about 72 sabins of absorption and a mean absorption of about 0.09, the tool uses the Sabine model and returns RT60 of about 2.9 s. The target band for 1,296 m3 is 1.60-2.20 s, so withinTarget is false: at 2.9 s the shell sits above the band and is too live.
02 / In depth
How this preset reads — the engineering view.
The geometry gives 792 m2 of total surface across a 1,296 m3 volume. The floor is 216 m2 of wood at a 1 kHz coefficient of 0.12 for 25.9 sabins, the ceiling 216 m2 of drywall at 0.08 for 17.3 sabins, and the walls 360 m2 of drywall at 0.08 for 28.8 sabins - about 72 sabins in total.
Because the mean absorption is only about 0.09, below the 0.2 point, the tool stays with the Sabine form and reports RT60 of about 2.9 s. For a large room this is a long, ringing decay.
The 1,296 m3 volume places the hall in the concert and large-auditorium band of 1.60-2.20 s. At 2.9 s the figure is above the band, so withinTarget is false - the bare shell is quantified as too live rather than assumed to be acceptable.
To move the room toward the band the tool recommends adding roughly 45 m2 of high-coefficient panel. This does not design the treatment layout; it estimates how much added absorber begins to close the gap between 2.9 s and the 1.60-2.20 s target.
What this preset deliberately does not solve
- withinTarget is false because 2.9 s is above the band, not in it.
- The 45 m2 absorber figure is a first-pass quantity, not a layout.
- Single 1 kHz band only; low-frequency ring is not modelled.
How this preset differs from its siblings
This preset is the untreated, too-live large room: 1,296 m3, only about 72 sabins, mean absorption 0.09, Sabine model, RT60 2.9 s above the 1.60-2.20 s band, with roughly 45 m2 of absorber recommended. The conference-room sibling is the opposite - a small 144 m3 room dressed on every surface to about 119 sabins, mean absorption 0.66, Eyring model, RT60 0.12 s and below its 0.50-0.70 s band with 0 m2 to add. Together they bracket the calculator: one shell needs absorber added, the other is over-treated.
03 / Hydrated calculator
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