Perfect pitch

Absolute pitch ("AP"), widely referred to as perfect pitch, refers to the ability to identify a note by name without the benefit of a reference note, or to be able to produce a note (as in singing) that is the correct pitch without reference.

Definition
Absolute pitch, in itself, can be defined as "the ability to attach labels to isolated auditory stimuli on the basis of pitch alone". Where a person with absolute pitch might be able to, for instance, identify the pitch of a car horn or be able to confirm when a piece is not played in its original key—often times, with varying degrees of conscious awareness in doing so.

Absolute pitch is difficult to accurately define in simplistic terms. In understanding absolute pitch, one should be aware that it is possible to have varying degrees of both absolute and relative pitch; with varying degrees of absolute pitch defined as being either "active" or "passive", and varying degrees of relative pitch that can range from highly accurate to "tone-deaf".

Distinctions
The musicologist Richard Parncutt and the cognitive psychologist Daniel Levitin introduced the following distinctions in their entry on absolute pitch in the New Grove Dictionary of Music and Musicians.

"Passive" absolute pitch
Persons with passive absolute pitch are able to identify individual notes that they hear, and can identify the key of a composition (assuming some degree of musical knowledge). Some may be able to identify several notes played simultaneously, and therefore identify complex chords. Those with passive absolute pitch are not always capable of singing a given note on command.

"Active" absolute pitch
Persons with active absolute pitch are able to sing any given note on queue, without prior pitch references. Usually, people with active absolute pitch are not only able to identify a note, but can recognize when that note is slightly sharp or flat. Active absolute pitch possessors in the United States number about 1 in every 10,000. However, in other locations, the population incidence has been measured at about 1 in 20.

Not all people with active absolute pitch are musicians. However, musical training is necessary for full development of the auditory potential of a person with absolute pitch.

Among the autistic and savant community, the incidence of absolute pitch rises to 1 in 20 or higher. Perfect pitch is also common among those with Williams syndrome.

Absolute pitch as a difference in cognition, not elementary sensation
Absolute pitch is not limited to the realm of music, or even to humans. Songbirds and wolves have exhibited the ability. In fact, studies indicate that absolute pitch is more a linguistic ability than a musical one. Absolute pitch is an act of cognition, needing memory of the frequency, a label for the frequency (such as B-flat), and exposure to the common range considered a note. (A note in modern tuning can vary in its exact frequency.) It may be directly analogous to recognizing colours, phonemes (speech sounds) or other categorical perception of sensory stimuli. And while most people have been trained to recognize and name the colour blue by its frequency, it is possible that only those who have had early (somewhere between the ages of 3 and 6) and deliberate exposure to the names of musical tones&mdash;usually musicians&mdash;will be likely to identify a middle C. Absolute pitch, however, may be genetic, possibly an autosomal dominant genetic trait, though it "might be nothing more than a general human capacity whose expression is strongly biased by the level and type of exposure to music that people experience in a given culture."

It has been shown possible to learn the naming of tones later in life, although arguably this skill is not true absolute pitch. However, with practice and dedication, the earnest student with good ears can improve in pitch identification.

Absolute pitch and linguistics
Perfect pitch is more common among speakers of tonal languages such as most dialects of Chinese or Vietnamese, which depend heavily on pitch for lexical meaning. "Tone deafness" is unusual among native speakers of these languages. Speakers of Sino-Tibetan languages have been reported to speak a word in the same absolute pitch (within a quarter-tone) on different days. It has therefore been suggested that absolute pitch may be acquired by infants when they learn to speak in a tonal language (and possibly also by infants when they learn to speak in a pitch stress language). Such individuals may be more likely to acquire absolute pitch for musical tones when they later receive musical training.

It is important to note that level-tone languages, which are found in Africa, such as Yoruba (with three pitch levels) and Mambila (with four pitch levels), are much better suited to study the role of absolute pitch in speech than the contour-tone languages of East Asia.

Further, speakers of European languages were found to make use of an absolute, though subconscious, pitch memory when speaking.

Nature or nurture?
Until the middle of the 20th century, most people believed that musical ability itself was an inborn talent. Some scientists believe absolute pitch may have an underlying genetic basis and are trying to locate genetic correlates; most believe that the acquisition of absolute pitch requires early training during a critical period of development, regardless of whether or not a genetic predisposition toward development exists or not. The "unlearning theory," first proposed by Abraham (1901) has recently been revived by developmental psychologists who argue that every person possesses absolute pitch (as a mode of perceptual processing) when they are infants, but that a shift in cognitive processing styles (from local, absolute processing to global, relational processing) causes most people to unlearn it; or, at least, causes children with musical training to discard absolute pitch as they learn to identify musical intervals. Additionally, any nascent absolute pitch may be lost simply by the lack of reinforcement or lack of clear advantages in most activities the developing child is involved with. A final resolution to the ongoing debate would require controlled experiments, which are both impractical and unethical.

It is nevertheless becoming increasingly accepted that some people can acquire absolute pitch (at least for single instruments) through directed learning. Pitch recognition is now taught at Julliard and the Eastman School of Music, and various "perfect pitch" courses have been offered since the early 1980s. Despite claims to the contrary in advertising campaigns, independent research at Ohio State University and the University of Calgary have failed to demonstrate statistically significant improvements in absolute pitch skills among students using a perfect pitch method developed by David Lucas Burge. To date, no scientifically documented evidence exists of an adult acquiring absolute pitch.

Potential problems
Persons who have absolute pitch may be irritated when a piece is transposed to a different key (or played at a nonstandard pitch). They may have a harder time developing relative pitch than others when following standard curricula, and the learning of tasks such as transposition may be hindered by an attempt to use their absolute knowledge for something that is better a relative task. Because their comprehension of musical pitch is categorical rather than spectral (Harris, 1974), poorly-trained absolute pitch possessors can find it quite difficult to play in tune with an orchestra which is not tuned to standard concert pitch A4 = 440 Hertz. These problems can be overcome by careful training designed to make sure the relative-pitch faculties are also developed.

Some countries have standardised to A4 = 442 Hz, while others have A4 = 440 Hz, so people from different countries with perfect pitch can find it hard to make music together.

Correlation with musical talent
There is no necessary correlation between the possession of absolute pitch and musical genius. Wolfgang Amadeus Mozart, Franz Liszt, Frédéric Chopin and Ludwig van Beethoven are some of the classical composers/musicians who had perfect pitch; Joseph Haydn, Igor Stravinsky, Maurice Ravel, Johannes Brahms, and Richard Wagner are among those who did not. Absolute pitch is not a prerequisite for developing high talent as a musician or composer.

Relative pitch
Many musicians, and most jazz musicians, have quite good relative pitch, a skill which can certainly be learned. With practice, it is possible to listen to a single known pitch once (from a pitch pipe or a tuning fork) and then have stable, reliable pitch identification by comparing the notes heard to the stored memory of the tonic pitch. Unlike true perfect pitch, this skill is dependent on a recently-perceived tonal center.