Pitch is the property of a sound that allows the construction of melodies; pitches are compared as "higher" and "lower", and are quantified as
frequenciesFrequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency....
(cycles per second, or
hertzThe hertz is a unit of frequency. It is defined as the number of complete cycles per second. It is the basic unit of frequency in the International System of Units , and is used worldwide in both general-purpose and scientific contexts...
), corresponding very nearly to the repetition rate of sound waves.
Pitch is not an objective physical property, but a subjective
psychophysicalPsychophysical may refer to:*Psychophysics, the subdiscipline of psychology dealing with the relationship between physical stimuli and their subjective correlates, or percepts...
attribute of
soundSound is a travelling wave which is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.- Perception of sound...
.
The perceived pitch of a
sine waveThe sine wave or sinusoid is a function that occurs often in mathematics, music, physics, signal processing, audition, electrical engineering, and many other fields...
is primarily related to its
frequencyFrequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency....
, though the
sound pressureSound pressure is the local pressure deviation from the ambient pressure caused by a sound wave. Sound pressure can be measured using a microphone in air and a hydrophone in water. The SI unit for sound pressure is the pascal...
of the tone can have a minor effect.
Pitch is the property of a sound that allows the construction of melodies; pitches are compared as "higher" and "lower", and are quantified as
frequenciesFrequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency....
(cycles per second, or
hertzThe hertz is a unit of frequency. It is defined as the number of complete cycles per second. It is the basic unit of frequency in the International System of Units , and is used worldwide in both general-purpose and scientific contexts...
), corresponding very nearly to the repetition rate of sound waves.
Pitch is not an objective physical property, but a subjective
psychophysicalPsychophysical may refer to:*Psychophysics, the subdiscipline of psychology dealing with the relationship between physical stimuli and their subjective correlates, or percepts...
attribute of
soundSound is a travelling wave which is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.- Perception of sound...
.
The perceived pitch of a
sine waveThe sine wave or sinusoid is a function that occurs often in mathematics, music, physics, signal processing, audition, electrical engineering, and many other fields...
is primarily related to its
frequencyFrequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency....
, though the
sound pressureSound pressure is the local pressure deviation from the ambient pressure caused by a sound wave. Sound pressure can be measured using a microphone in air and a hydrophone in water. The SI unit for sound pressure is the pascal...
of the tone can have a minor effect. Sounds more complex than a pure sine wave also have pitch, notably speech and musical notes. Many such sounds are approximately periodic, and the perceived pitch is directly related to the period. They also have a
spectrumA spectrum is a condition that is not limited to a specific set of values but can vary infinitely within a continuum. The word saw its first scientific use within the field of optics to describe the rainbow of colors in visible light when separated using a prism; it has since been applied by...
that is (approximately) a stack of harmonics, and the perceived pitch is related to the harmonic spacing. The lowest harmonic in the stack is called the
fundamental frequencyThe fundamental tone, often referred to simply as the fundamental and abbreviated f
0 or F
0, is the lowest frequency in a harmonic series....
, and its frequency is also strongly correlated with the pitch, though a strong pitch may be perceived even when the fundamental is missing.
Other complex sounds may have several pitches. A complex tone composed of two sine waves of 1000 and 1200 Hz will have three pitches. Two spectral pitches at 1000 and 1200 Hz, derived from the physical frequencies of the pure tones; and one "virtual pitch" at 200 Hz, derived from the repetition rate of the waveform. Sounds that do not have a period may also have a pitch, often dominated by the near-periodicity of the envelope or fine structure of the waveform.
Historically, the study of pitch perception, and especially of pitch in the case of the
missing fundamentalA sound is said to have a missing fundamental, suppressed fundamental, or phantom fundamental when its overtones suggest a fundamental frequency but the sound lacks a component at the fundamental frequency itself....
, has been a central problem in
psychoacousticsPsychoacoustics is the study of subjective human perception of sounds. Alternatively it can be described as the study of the psychological correlates of the physical parameters of acoustics.- Background :...
, and has been very instrumental in forming and testing theories of sound representation, processing, and perception in the
auditory system- Ear :- Outer ear :The folds of cartilage surrounding the ear canal are called the pinna. Sound waves are reflected and attenuated when they hit the pinna, and these changes provide additional information that will help the brain determine the direction from which the sounds came.The sound waves...
.
Some theories of pitch perception hold that pitch has inherent
octaveIn music, an octave , is the interval between one musical pitch and another with half or double its frequency. The octave relationship is a natural phenomenon which has been referred to as the "basic miracle of music," the use of which is "common in most musical systems." It may be derived from the...
ambiguities, and therefore is best decomposed into a pitch
chroma, a periodic value around the octave, like the note names in western music, and a pitch
height, which may be ambiguous, indicating which octave the pitch may be in.