Rehearsal Room Design Calculator

This calculator sizes a band or ensemble rehearsal room around three real acoustic constraints: floor space per musician, reverberation time, and expected sound level. Minimum space scales with how loud the instrumentation is — 25 square feet per player for acoustic instruments, 35 for amplified, and 50 once a full drum kit and amps are in the mix, since louder, bulkier setups need more separation to avoid feedback and physical crowding. Target reverberation time (RT60) shortens as instrumentation gets louder, too: 0.8 seconds for acoustic ensembles down to 0.4 seconds for drums-and-amps, because a longer decay time on loud sources quickly turns into muddiness. Estimated SPL starts from a baseline per instrument category (85/100/110 dB) and is adjusted logarithmically for group size, reflecting how sound energy from multiple simultaneous sources combines — doubling the players doesn't double the dB, it adds a few dB per doubling.

Anything estimated above 85 dB flags a hearing-protection recommendation, matching the threshold commonly used for extended daily noise exposure. The absorption treatment figure uses the Sabine reverberation formula, converting your room's volume and target RT60 into a required absorption in sabins, then subtracts the bare-room absorption estimate (assuming untreated surfaces have only about a 5% absorption coefficient) to find how much acoustic panel area, at roughly 80% absorption efficiency, needs adding. Ventilation is a flat 30 CFM per musician, a standard fresh-air allowance for continuous occupancy, not adjusted for exertion level from playing.