ABSTRACT
Loudness is an obvious characteristic of all sounds and has an enormous range. One can distinguish the loudness of two sounds that differ in intensity by only 1 dB, and this sensitivity is true over a range of 1012 W. Loudness judgments are subjective; loudness is a psychological dimension, not a physical one, and judgments of loudness will have considerably more variability than will measurements of intensity discrimination. The objective in measuring loudness is to attach a number to any possible sound which will represent its loudness. The question of equal loudness contours was one of the earliest raised. In principle its answer involves a simple method. The experimenter selects two different sinusoids or noise bands and the subject adjusts one in level until the loudnesses are equal. Loudness level in principle solves the problem of constructing a scale of loudness. In practice it may be difficult to match the sound to the standard tone.
