Worked Example: Opera House — ISO 3382 Vocal Projection Design
6000 m³ opera house with plaster ceiling, 600 upholstered seats, and QRD diffusers
A 6000 m³ concert hall designed to ISO-3382 requires RT60 ≤ 1.6s. With Painted plaster on the ceiling, the calculated RT60 is 1.73s — MARGINAL.
Room Setup
Total surface area: 2658.0 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| Ceiling — plaster | Painted plaster | 750.0 | 0.04 |
| Floor — carpet aisles | Heavy carpet | 350.0 | 0.29 |
| Floor — timber stalls/stage | Timber floor (sealed) | 400.0 | 0.09 |
| Walls — plaster | Painted plaster | 400.0 | 0.04 |
| Walls — QRD diffusers | QRD diffuser (wooden) | 80.0 | 0.14 |
| Seating (600 seats) | Upholstered seating | 420.0 | 0.55 |
| Curtains (proscenium) | Curtains (medium weight) | 60.0 | 0.56 |
| Box fronts — timber | Timber floor (sealed) | 60.0 | 0.09 |
| Walls — plaster (boxes) | Painted plaster | 80.0 | 0.04 |
| Fabric panels (box rear) | Fabric-wrapped panel 50mm | 50.0 | 0.78 |
| Doors | Solid timber door | 8.0 | 0.09 |
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 = 30 × 25 × 8 = 6000 m³
- 2
Total Surface Area
Stotal = 750.0 + 350.0 + 400.0 + 400.0 + 80.0 + 420.0 + 60.0 + 60.0 + 80.0 + 50.0 + 8.0 = 2658.0 m²
- 3
Absorption per Surface at 500 Hz
Ceiling — plaster: 750.0 m² × 0.04 = 30.00 Sabins
Floor — carpet aisles: 350.0 m² × 0.14 = 49.00 Sabins
Floor — timber stalls/stage: 400.0 m² × 0.10 = 40.00 Sabins
Walls — plaster: 400.0 m² × 0.04 = 16.00 Sabins
Walls — QRD diffusers: 80.0 m² × 0.15 = 12.00 Sabins
Seating (600 seats): 420.0 m² × 0.56 = 235.20 Sabins
Curtains (proscenium): 60.0 m² × 0.49 = 29.40 Sabins
Box fronts — timber: 60.0 m² × 0.10 = 6.00 Sabins
Walls — plaster (boxes): 80.0 m² × 0.04 = 3.20 Sabins
Fabric panels (box rear): 50.0 m² × 0.78 = 39.00 Sabins
Doors: 8.0 m² × 0.08 = 0.64 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 30.00 + 49.00 + 40.00 + 16.00 + 12.00 + 235.20 + 29.40 + 6.00 + 3.20 + 39.00 + 0.64 = 460.44 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 6000 / 460.44 = 2.10s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 1.73s. Target: 1.2--1.6s per ISO-3382. Verdict: MARGINAL
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 192.9 | 317.0 | 460.4 | 600.7 | 650.9 | 656.1 |
| RT60 (s) | 5.01 | 3.05 | 2.10 | 1.61 | 1.48 | 1.47 |
| Target (s) | — | — | 1.60 | 1.60 | 1.60 | — |
| Verdict | — | — | FAIL | MARGINAL | PASS | — |
Compliance Verdict
Reference:
Open the AcousPlan calculator pre-loaded with the exact room dimensions (30m × 25m × 8m) and RT60 target (1.6s).
Open CalculatorField Story
A new 600-seat opera house in Barcelona follows the traditional horseshoe plan with three tiers of boxes. Opera demands shorter RT60 than symphonic halls because vocal text intelligibility is paramount. Painted plaster ceiling and walls reflect sound efficiently, preserving vocal formants across the orchestra pit. QRD diffusers on rear walls of each box tier scatter reflections preventing discrete echoes. The 600 upholstered seats and carpeted aisles provide the absorption to control the RT60. Fabric-wrapped panels at the rear of each box provide targeted mid-frequency absorption. Heavy stage curtains offer variable absorption for different productions. ISO 3382-1 recommends 1.2-1.6 s for opera — shorter than symphony to prioritise vocal clarity while maintaining orchestral warmth.
Frequently Asked Questions
What RT60 does a Opera House — ISO 3382 Vocal Projection Design achieve?
With the specified materials and dimensions (30m x 25m x 8m, volume 6000m3), the calculated mid-frequency RT60 is 1.73s using the Sabine equation. The target under ISO-3382 is 1.2--1.6s. The result is a MARGINAL.
What materials are used in this performance acoustic example?
This example uses Painted plaster on the Ceiling — plaster (NRC 0.04), Heavy carpet on the Floor — carpet aisles (NRC 0.29), Timber floor (sealed) on the Floor — timber stalls/stage (NRC 0.09), Painted plaster on the Walls — plaster (NRC 0.04), QRD diffuser (wooden) on the Walls — QRD diffusers (NRC 0.14), Upholstered seating on the Seating (600 seats) (NRC 0.55), Curtains (medium weight) on the Curtains (proscenium) (NRC 0.56), Timber floor (sealed) on the Box fronts — timber (NRC 0.09), Painted plaster on the Walls — plaster (boxes) (NRC 0.04), Fabric-wrapped panel 50mm on the Fabric panels (box rear) (NRC 0.78), Solid timber door on the Doors (NRC 0.09). The total absorption at 500 Hz is 460.4 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.
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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.