phon
/fɑn/
noun
- A unit of loudness of sound, equal to the intensity of a tone of a given frequency that is perceived to be as loud as a reference tone of 1000 hertz at a certain decibel level.
- A whisper is about 20 phons, while a jet engine can reach 120 phons.
- The phon scale helps engineers design quieter appliances.
- The noise level in the factory was measured at 85 phons.