— 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
Try the configuration — live.
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— Acoustic · RT60 · Sabine / Eyring · ISO 3382
The room's reverberation time.
Sabine equation (RT60 = 0.161 × V / A) with 1 kHz absorption coefficients — a single-band brief-stage estimator that switches to the Eyring form once mean absorption passes ᾱ ≈ 0.2, where Sabine over-reads. Production design always runs octave-band (125 Hz – 4 kHz) and validates on-site with an ISO 3382 impulse measurement.
Premium consultation · Concert hall / large auditorium
2.90 s RT60
Outside target — the concert hall / large auditorium band sits at 1.60–2.20 s. Total absorption is 72.0 Sabins across 1296 m³.
Room volume
1296 m³
Concert hall / large auditorium
Calculated RT60
2.90 s
Outside target
Total absorption
72.0 Sabins
Σ surface × coefficient
Target band
1.60 – 2.20 s
for this volume
Recommended absorber treatment
≈ 35–54 m²
Indicative range · 50 mm fabric-wrapped panel, distributed across walls + ceiling — confirm the quantity with octave-band modelling
Assumptions driving this recommendation↓ expand
- Floor
- Wood / wood panelling (α = 0.12)
- Walls
- Painted drywall (α = 0.08)
- Ceiling
- Painted drywall (α = 0.08)
- Method
- Sabine equation, 1 kHz single-band
- Measurement standard
- ISO 3382 impulse measurement (on-site validation)
- Production model
- Octave-band 125 Hz – 4 kHz · EASE / Treble
- Panel α
- 0.85 (premium 50 mm fabric-wrapped)
- Dedicated cinema rooms
- ≈ 0.40 – 0.70 s target (SMPTE / Dolby guidance) — see Cinema Sizer
Operationally sensible ecosystem
Brands grouped by engineering role — not random logos.
Loudspeakers
LCR / surround / overhead arrays
- KEF ReferenceAudiophile-grade home cinema
- JBL SynthesisPro-cinema lineage for residential
- Sonance ReferenceArchitectural reference series
Amplification
Multi-channel + multi-room
- Crown DCi NetworkTouring-grade install amp
- Lab.gruppen ECompact multi-channel install
AV distribution
Matrix + AV-over-IP + endpoints
- Crestron DM NVXAV-over-IP 4K60
- Crestron DM 8K8K HDBaseT matrix
The Sabine / Eyring model is a first-order estimator — a single 1 kHz coefficient does not capture low-frequency modal behaviour or high-frequency air absorption. Production design always runs octave-band (125 Hz – 4 kHz) modelling in EASE / Treble and validates on-site with a calibration microphone + impulse measurement per ISO 3382 before committing specification. Dedicated cinema / mastering rooms follow much lower, tighter reverberation targets (≈ 0.4 – 0.7 s per SMPTE / Dolby guidance) — size those with the Cinema Sizer brief, not this speech-band estimator.
A planning link that reopens this exact configuration — not a quote.
Next step
Take this acoustic target to the AV desk.
This Sabine estimate is an indicative planning figure, not a final design. A short brief lets us run octave-band modelling and validate on-site with an impulse measurement.
· Other presets for rt60 acoustic calculator
· Next
Brief us on the project — with this configuration.
Presets are a typology starting point. The brief wizard captures the room geometry, programme and constraints we need to translate this configuration into a real design.