Worked Example: Recital Hall — ISO 3382 Chamber Music Design
1500 m³ timber-lined recital hall with QRD diffusers and 300 upholstered seats
A 1500 m³ concert hall designed to ISO-3382 requires RT60 ≤ 1.8s. With Timber floor (sealed) on the ceiling, the calculated RT60 is 1.23s — MARGINAL.
Room Setup
Total surface area: 1212.0 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| Ceiling — timber | Timber floor (sealed) | 375.0 | 0.09 |
| Floor — timber | Timber floor (sealed) | 280.0 | 0.09 |
| Floor — carpet aisles | Heavy carpet | 95.0 | 0.29 |
| Walls — plaster | Painted plaster | 200.0 | 0.04 |
| Walls — QRD diffusers | QRD diffuser (wooden) | 60.0 | 0.14 |
| Walls — timber panelling | Timber floor (sealed) | 40.0 | 0.09 |
| Seating (300 seats) | Upholstered seating | 150.0 | 0.55 |
| Windows | Double glazing 6mm | 12.0 | 0.03 |
Absorption coefficients sourced from manufacturer datasheets and ISO 354 test reports. Browse the full acoustic materials database.
Step-by-Step Calculation
- 1
Room Volume
V = L × W × H = 25 × 15 × 4 = 1500 m³
- 2
Total Surface Area
Stotal = 375.0 + 280.0 + 95.0 + 200.0 + 60.0 + 40.0 + 150.0 + 12.0 = 1212.0 m²
- 3
Absorption per Surface at 500 Hz
Ceiling — timber: 375.0 m² × 0.10 = 37.50 Sabins
Floor — timber: 280.0 m² × 0.10 = 28.00 Sabins
Floor — carpet aisles: 95.0 m² × 0.14 = 13.30 Sabins
Walls — plaster: 200.0 m² × 0.04 = 8.00 Sabins
Walls — QRD diffusers: 60.0 m² × 0.15 = 9.00 Sabins
Walls — timber panelling: 40.0 m² × 0.10 = 4.00 Sabins
Seating (300 seats): 150.0 m² × 0.56 = 84.00 Sabins
Windows: 12.0 m² × 0.04 = 0.48 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 37.50 + 28.00 + 13.30 + 8.00 + 9.00 + 4.00 + 84.00 + 0.48 = 184.28 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 1500 / 184.28 = 1.31s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 1.23s. Target: 1.4--1.8s per ISO-3382. Verdict: MARGINAL
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 147.4 | 154.3 | 184.3 | 200.7 | 206.4 | 215.1 |
| RT60 (s) | 1.64 | 1.57 | 1.31 | 1.20 | 1.17 | 1.12 |
| Target (s) | — | — | 1.80 | 1.80 | 1.80 | — |
| Verdict | — | — | MARGINAL | MARGINAL | FAIL | — |
Compliance Verdict
Reference:
Open the AcousPlan calculator pre-loaded with the exact room dimensions (25m × 15m × 4m) and RT60 target (1.8s).
Open CalculatorField Story
A music conservatoire in Zurich is building a 300-seat recital hall for chamber music and solo recitals. The 25 m by 15 m room is lined in European oak — ceiling and wall panels — creating the warm resonant acoustic that string quartets prefer. Timber surfaces reflect and diffuse sound while absorbing selectively at low frequencies through panel resonance. QRD diffusers on the rear wall prevent focused reflections returning to the stage. Generously carpeted aisles provide mid-frequency absorption while the timber floor under seats reflects energy upward to the ceiling. The upholstered seats are the primary absorber, selected to match average audience absorption so that rehearsals and performances sound consistent. ISO 3382-1 recommends 1.4-1.8 s for chamber music — slightly shorter than a symphony hall to preserve clarity of intimate textures.
Frequently Asked Questions
What RT60 does a Recital Hall — ISO 3382 Chamber Music Design achieve?
With the specified materials and dimensions (25m x 15m x 4m, volume 1500m3), the calculated mid-frequency RT60 is 1.23s using the Sabine equation. The target under ISO-3382 is 1.4--1.8s. The result is a MARGINAL.
What materials are used in this performance acoustic example?
This example uses Timber floor (sealed) on the Ceiling — timber (NRC 0.09), Timber floor (sealed) on the Floor — timber (NRC 0.09), Heavy carpet on the Floor — carpet aisles (NRC 0.29), Painted plaster on the Walls — plaster (NRC 0.04), QRD diffuser (wooden) on the Walls — QRD diffusers (NRC 0.14), Timber floor (sealed) on the Walls — timber panelling (NRC 0.09), Upholstered seating on the Seating (300 seats) (NRC 0.55), Double glazing 6mm on the Windows (NRC 0.03). The total absorption at 500 Hz is 184.3 Sabins.
How much does acoustic treatment cost for this room?
Cost data is not available for this example. Use the AcousPlan calculator to estimate treatment costs for your specific room configuration.
Related Examples
Concert Hall — ISO 3382-1 Acoustic Performance
Cinema Auditorium — BS 8233 Low Reverberation Design
Rehearsal Room — DIN 18041 Music Practice Design
Opera House — ISO 3382 Vocal Projection Design
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All calculations are advisory and based on the Sabine equation (ISO 3382-2:2008 Annex A). Results require professional verification for compliance submissions. Absorption coefficients are sourced from manufacturer datasheets and ISO 354 test reports.