Pitch is a sensation that results from psychological response to frequency.
The range of audible frequencies for humans falls roughly between 20 and 20,000 Hz. Much research has been extended in finding correlations between pitch and frequency, where pitch is understood as a response pattern to the frequency of a sound. The goal is to be able to scale perceptual response to stimulus. S. S. Stevens conducted experiments in the 1930s in which subjects were given a keyboard with five keys similar to a piano keyboard. Subjects were asked to adjust the frequency for each of three intermediate keys until the difference, in pitch, between each key was judged to be the same.