Answer :
An equal loudness contour is a measure of sound pressure, 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 phon's 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contours are often referred to as "Fletcher-Munson" curves, after the earliest researchers, but those studies have been superseded and incorporated into newer standards. The definitive curves are those defined in the international standard ISO 226:2003, which are based on a review of modern determinations made in various countries.
Equal-loudness curve change as you age will decline as Fletcher-Munson curves stipulate. This is further explained below.
What is equal-loudness?
Equal-loudness is simply defined as a level of loudness that when delivered with pure steady tones, the contour is a measurement of sound depth over the frequency range for which a 2nd party perceives a steady loudness.
In conclusion, Equal-loudness varies with age.
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