Cornerstone Acoustics — design tool
Reverberation time calculator for school spaces
This tool is intended to provide indicative and early design advice for the room finishes in Education spaces. It is not a replacement for formal review by a competent Acoustics Consultant.
Enter room dimensions and finishes to estimate the mid-frequency reverberation time (500 Hz–2 kHz average), check it against BB93 design criteria, and see what it would take to bring a non-compliant room into range.
Room
Target shown: 0.6s.
Secondary general teaching spaces and practice rooms that are smaller than 30 metres cubed.
A standard flat-ceiling room with four vertical walls.
Finishes
Modelled as displacing an equal area of the wall finish above — panels, rafts or other treatments applied in front of a surface.
Result
2.56s
0.6s limit — music practice/ group room (≤30m^3)
Room volume: 129.0 m³
Floor area: 46.1 m² · Ceiling area: 46.1 m² · Wall area: 76.2 m² (of 76.2 m² total)
| Octave band | Absorption (m² sab) | RT (s) |
|---|---|---|
| 500 Hz | 7.97 | 2.60 |
| 1 kHz | 7.97 | 2.60 |
| 2 kHz | 8.44 | 2.46 |
| Average | — | 2.56 |
What would it take to comply?
Current build-up gives 2.56s against a 0.6s limit — 1.96s over.
Upgrade the ceiling to a Class A mineral tile.
Calculation info:
Reverberation time is estimated with the Sabine equation, RT = 0.161 × V ⁄ A, calculated independently in the 500 Hz, 1 kHz and 2 kHz octave bands and then averaged to give the BB93 mid-frequency figure. Absorption coefficients are Cornerstone Acoustics' own reference values for each finish category and will still vary between specific manufactured products — use tested data for detailed design. Targets shown are simplified from Building Bulletin 93 (2015), “Acoustic design of schools: performance standards,” for common room types under unoccupied conditions; some room types carry criteria that vary with volume or include additional requirements (e.g. speech intelligibility, background noise). Confirm the applicable criterion against the current edition of BB93 before certifying compliance. Pitched-roof geometry assumes a symmetric ridge running parallel to the room's length, with gable walls at each end.