Worked Example: Physiotherapy Gym — Excessive Reverberation
RT60 calculation for a hospital physiotherapy gym with painted plaster ceiling and concrete block walls. The hard surfaces and rubber floor create excessive reverberation, making patient-therapist communication difficult during rehabilitation sessions.
A 490 m³ gymnasium designed to BS-8233 requires RT60 ≤ 1s. With Painted plaster on the ceiling and Fabric-wrapped panel 50mm on walls, the calculated RT60 is 1.47s — FAIL.
Room Setup
Total surface area: 453.2 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| ceiling | Painted plaster | 140.0 | 0.04 |
| walls-main | Painted concrete block | 118.0 | 0.07 |
| walls-treatment | Fabric-wrapped panel 50mm | 28.0 | 0.80 |
| floor | Rubber sport floor | 140.0 | 0.08 |
| windows | Double glazing 6mm | 20.0 | 0.04 |
| door | Solid timber door | 7.2 | 0.08 |
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 = 14 × 10 × 3.5 = 490 m³
- 2
Total Surface Area
Stotal = 140.0 + 118.0 + 28.0 + 140.0 + 20.0 + 7.2 = 453.2 m²
- 3
Absorption per Surface at 500 Hz
ceiling: 140.0 m² × 0.04 = 5.60 Sabins
walls-main: 118.0 m² × 0.06 = 7.08 Sabins
walls-treatment: 28.0 m² × 0.78 = 21.84 Sabins
floor: 140.0 m² × 0.08 = 11.20 Sabins
windows: 20.0 m² × 0.04 = 0.80 Sabins
door: 7.2 m² × 0.08 = 0.58 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 5.60 + 7.08 + 21.84 + 11.20 + 0.80 + 0.58 = 47.10 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 490 / 47.10 = 1.67s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 1.47s. Target: ≤ 1s per BS-8233. Verdict: FAIL
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 27.0 | 32.8 | 47.1 | 57.0 | 57.8 | 55.2 |
| RT60 (s) | 2.92 | 2.40 | 1.67 | 1.38 | 1.36 | 1.43 |
| Target (s) | — | — | 1.00 | 1.00 | 1.00 | — |
| Verdict | — | — | FAIL | FAIL | FAIL | — |
Compliance Verdict
Reference: BS 8233:2014 Table 4; HTM 08-01
Physiotherapy gyms share the acoustic challenges of sports halls but with the added requirement for clear verbal instruction during rehabilitation. Many hospital physio gyms fail acoustic standards due to untreated hard surfaces.
STI result: 0.45 (per IEC 60268-16:2020)
Cost Estimate
Costs are indicative and vary by region, supplier, and installation complexity. For a detailed cost breakdown, use the AcousPlan calculator.
Open the AcousPlan calculator pre-loaded with the exact room dimensions (14m × 10m × 3.5m) and RT60 target (1s).
Open CalculatorField Story
Physiotherapists at a rehabilitation hospital report that they must shout to give patients instructions during exercises, and patients with brain injuries or cognitive impairment become confused by the reverberant environment. The gym occupies a converted warehouse space with painted concrete block walls, a plaster ceiling, and rubber flooring required for dropped-weight safety. The RT60 of over 1.4 seconds makes group exercise classes particularly challenging. Despite clear evidence of impact on patient outcomes, the capital works team struggles to fund a ceiling retrofit because acoustic treatment is not classified as clinical equipment. The acoustic consultant produces a cost-benefit analysis showing that improved communication could reduce average rehabilitation time by 15%, eventually securing funding.
Frequently Asked Questions
What RT60 does a Physiotherapy Gym — Excessive Reverberation achieve?
With the specified materials and dimensions (14m x 10m x 3.5m, volume 490m3), the calculated mid-frequency RT60 is 1.47s using the Sabine equation. The target under BS-8233 is 1s or less. The result is a FAIL.
What materials are used in this healthcare acoustic example?
This example uses Painted plaster on the ceiling (NRC 0.04), Painted concrete block on the walls-main (NRC 0.07), Fabric-wrapped panel 50mm on the walls-treatment (NRC 0.8), Rubber sport floor on the floor (NRC 0.08), Double glazing 6mm on the windows (NRC 0.04), Solid timber door on the door (NRC 0.08). The total absorption at 500 Hz is 47.1 Sabins.
How much does acoustic treatment cost for this room?
The estimated treatment cost is £1,400 for 28 m2 of absorptive material at approximately £50/m2. Actual costs vary by region, supplier, and installation complexity.
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GP Consulting Room — Speech Privacy Design
School Gymnasium — BB93 Non-Compliant Case
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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.