Alternative term: Equivalent loudness
The loudness level of a sound is the sound pressure level of a standard pure tone (1000 Hz) which, according to the median value of judgements of normal observers, is assessed as being equally loud with the sound.
Note: The unit of loudness level is the Phon.
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
Celsius (previously Centigrade)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM