Sound Pressure Level

Sound pressure level


As the human ear can detect sounds with a very wide range of amplitudes, sound pressure is often measured as a level on a logarithmic decibel scale.
Since the human ear does not have a flat spectral response, sound pressure levels are often frequency weighted so that the measured level will match perceived levels more closely. The International Electrotechnical Commission (IEC) has defined several weighting schemes.

A-weighting attempts to match the response of the human ear to noise and A-weighted sound pressure levels are labeled dBA. C-weighting is used to measure peak levels.

Examples of sound pressure and sound pressure levelsSource of sound sound pressure sound pressure level pascal dB re 20 µPa threshold of pain 100 134 hearing damage during short-term effect 20 approx. 120 jet engine, 100 m distant 6–200 110–140 jack hammer, 1 m distant / discotheque 2 approx. 100 hearing damage during long-term effect 0.6 approx. 90 major road, 10 m distant 0.2–0.6 80–90 passenger car, 10 m distant 0.02–0.2 60–80 TV set at home level, 1 m distant 0.02 ca. 60 normal talking, 1 m distant 0.002–0.02 40–60 very calm room 0.0002–0.0006 20–30 leaves noise, calm breathing 0.00006 10 auditory threshold at 2 kHz 0.00002