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Question
What is meant by the ‘loudness’ of a sound? How is it related to the intensity?
Solution
Loudness is an aural sensation, i.e., a physiological rather than a physical phenomenon. It increases with intensity but the relation between the two is not linear, i.e., the ear does not recognize a sound, having twice the intensity of another, as twice as loud. In fact loudness (L) of a sound and its intensity (I) are related as L = k log (I/I0). Here I/I0 is the intensity level of the sound or the ratio between its intensity I and the zero of intensity or the threshold intensity I0 and k, a constant of proportionality depending upon the unit chosen.
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