Worked Example: Concert Hall — ISO 3382-1 Acoustic Performance
8000 m³ shoebox concert hall with QRD diffusers, 800 upholstered seats, and concrete ceiling
A 8000 m³ concert hall designed to ISO-3382 requires RT60 ≤ 2.2s. With Exposed concrete on the ceiling, the calculated RT60 is 2.31s — MARGINAL.
Room Setup
Total surface area: 3520.0 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| Ceiling — exposed concrete | Exposed concrete | 1000.0 | 0.02 |
| Floor — timber stage + under seats | Timber floor (sealed) | 700.0 | 0.09 |
| Floor — carpet aisles | Heavy carpet | 300.0 | 0.29 |
| Walls — plaster (upper) | Painted plaster | 600.0 | 0.04 |
| Walls — QRD diffusers | QRD diffuser (wooden) | 200.0 | 0.14 |
| Walls — plaster (lower/balcony) | Painted plaster | 200.0 | 0.04 |
| Seating (800 seats) | Upholstered seating | 480.0 | 0.55 |
| Curtains (variable) | Curtains (medium weight) | 40.0 | 0.56 |
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 = 40 × 25 × 8 = 8000 m³
- 2
Total Surface Area
Stotal = 1000.0 + 700.0 + 300.0 + 600.0 + 200.0 + 200.0 + 480.0 + 40.0 = 3520.0 m²
- 3
Absorption per Surface at 500 Hz
Ceiling — exposed concrete: 1000.0 m² × 0.02 = 20.00 Sabins
Floor — timber stage + under seats: 700.0 m² × 0.10 = 70.00 Sabins
Floor — carpet aisles: 300.0 m² × 0.14 = 42.00 Sabins
Walls — plaster (upper): 600.0 m² × 0.04 = 24.00 Sabins
Walls — QRD diffusers: 200.0 m² × 0.15 = 30.00 Sabins
Walls — plaster (lower/balcony): 200.0 m² × 0.04 = 8.00 Sabins
Seating (800 seats): 480.0 m² × 0.56 = 268.80 Sabins
Curtains (variable): 40.0 m² × 0.49 = 19.60 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 20.00 + 70.00 + 42.00 + 24.00 + 30.00 + 8.00 + 268.80 + 19.60 = 482.40 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 8000 / 482.40 = 2.67s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 2.31s. Target: 1.8--2.2s per ISO-3382. Verdict: MARGINAL
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 253.0 | 351.0 | 482.4 | 591.6 | 622.8 | 661.2 |
| RT60 (s) | 5.09 | 3.67 | 2.67 | 2.18 | 2.07 | 1.95 |
| Target (s) | — | — | 2.20 | 2.20 | 2.20 | — |
| Verdict | — | — | FAIL | PASS | PASS | — |
Compliance Verdict
Reference:
Open the AcousPlan calculator pre-loaded with the exact room dimensions (40m × 25m × 8m) and RT60 target (2.2s).
Open CalculatorField Story
A new 800-seat symphony concert hall in Vienna follows the classic shoebox design — 40 m long, 25 m wide, 8 m high — a geometry proven by the Musikverein and Boston Symphony Hall. The exposed concrete ceiling reflects sound energy back to the audience with minimal absorption, while timber flooring under seats projects instrument sound outward. QRD wooden diffusers on the side walls scatter lateral reflections creating the spatial impression (Lateral Fraction, LF) critical for orchestral envelopment. The 800 fully upholstered seats are the single largest absorber, ensuring consistent RT60 whether the hall is half or fully occupied. ISO 3382-1:2009 specifies the 1.8-2.2 s range as optimal for symphonic music; variable curtains behind the stage allow fine-tuning for chamber ensembles requiring shorter reverberation.
Frequently Asked Questions
What RT60 does a Concert Hall — ISO 3382-1 Acoustic Performance achieve?
With the specified materials and dimensions (40m x 25m x 8m, volume 8000m3), the calculated mid-frequency RT60 is 2.31s using the Sabine equation. The target under ISO-3382 is 1.8--2.2s. The result is a MARGINAL.
What materials are used in this performance acoustic example?
This example uses Exposed concrete on the Ceiling — exposed concrete (NRC 0.02), Timber floor (sealed) on the Floor — timber stage + under seats (NRC 0.09), Heavy carpet on the Floor — carpet aisles (NRC 0.29), Painted plaster on the Walls — plaster (upper) (NRC 0.04), QRD diffuser (wooden) on the Walls — QRD diffusers (NRC 0.14), Painted plaster on the Walls — plaster (lower/balcony) (NRC 0.04), Upholstered seating on the Seating (800 seats) (NRC 0.55), Curtains (medium weight) on the Curtains (variable) (NRC 0.56). The total absorption at 500 Hz is 482.4 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.
Related Examples
Recital Hall — ISO 3382 Chamber Music Design
Cinema Auditorium — BS 8233 Low Reverberation Design
Rehearsal Room — DIN 18041 Music Practice Design
Opera House — ISO 3382 Vocal Projection Design
Explore More
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.