Loudness level contour
Alternative term: Equivalent loudness contour
A contour on a graph, the co-ordinates of which are the frequency and the sound pressure level, joining all points of equal loudness level (equal equivalent loudness).
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