What the numbers mean
- Level: the loudness right now, averaged over a few milliseconds.
- Peak: the loudest single moment.
- Leq: the average level since you started (or reset), the figure noise limits use.
- Max: the highest level reached.
A weighting follows how the ear hears quiet sounds and is used for noise and hearing safety; C weighting keeps more of the bass and suits loud music; Z is flat.
About accuracy
A phone or laptop microphone is not a calibrated measuring instrument: the meter reads in dBFS (relative to the loudest sound the device can take) until you calibrate it. To read dB SPL, measure a steady sound with a real sound-level meter, enter the difference as the calibration offset, and switch on Show as dB SPL. Even then, treat the readings as a guide.
Safe listening
As a rough guide, long exposure above about 85 dB(A) can harm hearing; every 3 dB louder halves the safe time. Rehearsal rooms and concerts often exceed that: wear hearing protection.