About this tool
The Room Noise Level calculator estimates the background noise of a room and compares it against a target curve — Russian SanPiN 1.2.3685-21, international NC (Noise Criterion), or NR (Noise Rating). The tool takes sound pressure level by octave band from 63 Hz to 8 kHz or an overall dB(A) level, decomposes noise into three typical sources (HVAC, outdoor, internal), and outputs the actual room noise curve, the target curve for your scenario, and the excess at each octave band.
Why it matters: background noise is the invisible budget of sound quality. In a studio at 35 dB(A) ambient, quiet passages are mixed "blind": you cannot hear tails or noises below that level. In an office or coworking space, anything above NC-40 fatigues focused work within an hour. In a residential room, SanPiN 1.2.3685-21 allows no more than NC-25 at night — exceeding it means neighbour complaints have formal grounds.
How to read results: the red zone on the chart shows excess over the target curve; the green zone is silence headroom. Pay special attention to low frequencies (63–125 Hz): that's where HVAC and street-traffic boom usually shows up. The per-source breakdown tells you who is actually stealing decibels — this drives priority: a duct silencer, a window with higher Rw, vibration isolation, or quieter fans.
Common mistakes: judging by dB(A) alone — this single number hides narrow-band hum that, at the same 35 dB(A), is subjectively far more annoying than a flat spectrum; ignoring the octave-band shape — two rooms with identical overall level can feel completely different; forgetting internal sources (laptop fan, projector, a fridge through a thin partition).
Next steps: for outdoor noise, refine the window choice via the facade insulation calculator; for HVAC issues, design silencers and vibration isolation in the Treatment Planner. Before final commissioning, validate the estimate with a real measurement — a sound level meter or a calibrated microphone (REW/Smaart). The spectrum analyzer on the diagnostics page shows the overall spectrum at a glance.
