Which scientific unit gives a measure of loudness?
Loudness sounds, such as for broadcasting and cinema. Others, such as ISO 532A (Stevens loudness, measured in sones), ISO 532B (Zwicker loudness), DIN 45631 and ASA/ANSI S3.4, have a more general scope and are often used to characterize loudness of environmental noise. Loudness, a subjective measure, often confused with physical measures of sound strength such as sound pressure, sound pressure level (in decibels), sound intensity or sound power. Filters such as A-weighting and LKFS attempt to compensate measurements to correspond to loudness as perceived by the typical human. The perception of loudness is related to sound pressure level (SPL), frequency content
Equal-loudness contour Equal-loudness contour An equal-loudness contour is a measure of sound pressure (dB SPL), over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones. The unit of measurement for loudness levels is the phon, and is arrived at by reference to equal-loudness contours. By definition, two sine waves of differing frequencies are said to have equal-loudness level measured in phons if they are perceived as equally loud by the average young person without significant hearing impairment. Equal-loudness contours are often referred to as "Fletcher-Munson" curves, after the earliest researchers, but those studies have