For example, an AP possessor can accurately reproduce a heard tone on a musical instrument without "hunting" for the correct pitch.
For example, the note known as 'A' varied in different local or national musical traditions between what is considered as G sharp and B flat before the standardisation of the late 19th century.
Absolute pitch may be directly analogous to recognizing colors, phonemes (speech sounds), or other categorical perception of sensory stimuli.
For example, most people have learned to recognize and name the color blue by the range of frequencies of the electromagnetic radiation that are perceived as light; those who have been exposed to musical notes together with their names early in life may be more likely to identify the note C.[19] Although it was once thought that 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",[20] absolute pitch may be influenced by genetic variation, possibly an autosomal dominant genetic trait.
[21][22][23][24][25] Evidence suggests that absolute pitch sense is influenced by cultural exposure to music, especially in the familiarization of the equal-tempered C-major scale.
One study of Dutch non-musicians also demonstrated a bias toward using C-major tones in ordinary speech, especially on syllables related to emphasis.
[27] Absolute pitch is more common among speakers of tonal languages, such as most dialects of Chinese or Vietnamese, which depend on pitch variation to distinguish words that otherwise sound the same—e.g., Mandarin with four possible tonal variations, Cantonese with nine, Southern Min with seven or eight (depending on dialect), and Vietnamese with six.
Many native speakers of a tone language, even those with little musical training, are observed to sing a given song with consistent pitch.
While the boundaries of musical pitch categories vary among human cultures, the recognition of octave relationships is a natural characteristic of the mammalian auditory system.
[45] Absolute pitch does not depend upon a refined ability to perceive and discriminate gradations of sound frequencies,[46] but upon detecting and categorizing a subjective perceptual quality typically referred to as "chroma".
[48] The prevalence of absolute pitch is higher among those who are blind from birth as a result of optic nerve hypoplasia.
[clarification needed][59] However, the converse is not indicated by research which found no difference between those with absolute pitch and those without on measures of social and communication skills, which are core deficits in autistic spectrum disorders.
[23][25][24] Researchers have been trying to teach absolute pitch ability in laboratory settings for more than a century,[69] and various commercial absolute-pitch training courses have been offered to the public since the early 1900s.
When tested, these students did not succeed in singing the memorized Suzuki songs in the original, fixed key.
Because absolute listeners are capable of recognizing that a musical composition has been transposed from its original key, or that a pitch is being produced at a nonstandard frequency (either sharp or flat), a musician with absolute pitch may become confused upon perceiving tones believed to be "wrong" or hearing a piece of music "in the wrong key".
When playing in groups with other musicians, this may lead to playing in a tonality that is slightly different from that of the rest of the group, such as when soloists tune slightly sharp of the rest of the ensemble to stand out or to compensate for loosening strings during longer performances.