The study of pitch dates back to at least the time of Pythagoras, who formulated the relationship between the length of a string and the pitch it would produce if it were strummed. The perception of pitch is the basis of musical melody and the voicing of speech; moreover, pitch is an attribute of the sound created by many objects in our world.

While the common definition of pitch has to do with a subjective attribute of sound and is scaled from low to high, pitch is closely related to frequency, a physical attribute of sound. The other physical attributes of sound are level, temporal structure, and complexity (Rossing, 1990). The study of pitch perception is often linked to the ability of the auditory system to process the frequency content of sound. The physical attributes of sound are derived from the fact that sound occurs when objects vibrate. The rate at which an object vibrates in an oscillatory manner is the frequency of the sound. If an object vibrates back and forth in a regular and repeatable manner 440 times in 1 s, it is said to have a frequency of 440 cycles per second (cps), which is indicated as 440 Hz (Hertz). If this vibrating object generated sound, the sound would have a 440-Hz frequency. If the vibrating object were a guitar string, a musician would perceive the vibrating string to have a pitch of 440 Hz. A higher rate of vibration would produce a higher pitch and a lower rate a lower pitch. Thus, for the vibrating guitar string, pitch is the subjective attribute of frequency. The relationship between the physical attributes of sound and pitch is not as simple as the guitar-string example suggests, and a few of the complexities will be described later in this article. That is, frequency and pitch are not synonymous.

Frequency can be measured using physical or objective means to determine the rate of vibration (Rossing, 1990). The measurement of pitch requires perceptual measurement techniques found in the research toolbox of the psychoacoustician or the musician. In many contexts, the pitch of a test sound is determined by comparing its perceived pitch with that of a standard sound. The standard sound is usually a sound with a very regular vibratory pattern, such as a tone or a periodic train of brief impulses (a click train). If the comparison sound and the test sound are judged to have the same perceived pitch, then the pitch of the test sound is the vibratory frequency of the comparison sound. So, in the example involving the guitar string, the vibrating string would be perceived as having the same pitch as a tone or a click train with a 440-Hz frequency.