Only about 1 in every 10,000 people has "perfect pitch", the ability to identify a musical note just by hearing it, with no reference note.
Absolute pitch (AP), often called perfect pitch, is a rare ability of a person to identify or re-create a given musical note without the benefit of a reference tone. AP can be demonstrated via linguistic labeling ("naming" a note), auditory imagery, or sensorimotor responses. For example, an AP possessor can accurately reproduce a heard tone on a musical instrument without "hunting" for the correct pitch. The frequency of AP in the general population is not known. The assumed occurrence of less than 1:10,000 is widely reported, but it is not supported by evidence. However, a review of more recent and international studies indicates the prevalence of at least 4% amongst music students.
Generally, absolute pitch implies some or all of the following abilities, achieved without a reference tone:
Identify by name individual pitches played on various instruments.
Name the key of a given piece of tonal music.
Identify and name all the tones of a given chord or other tonal mass.
Accurately sing a named pitch.
Name the pitches of common everyday sounds such as car horns and alarms.
People may have absolute pitch along with the ability of relative pitch, and relative and absolute pitch work together in actual musical listening and practice, but strategies in using each skill vary.
Adults who possess relative pitch but do not already have absolute pitch can learn "pseudo-absolute pitch" and become able to identify notes in a way that superficially resembles absolute pitch. Certain people who train to name notes may indeed become able to identify all 12 notes of the scale with 90% accuracy or above, and valproate, a medication used to treat epilepsy and severe depression, may re-open the "critical period" of learning, acquiring absolute pitch, as well as languages, potentially as efficient for adults as for children. Even so, pitch training can require considerable motivation, time, and effort, and learning is not retained without constant practice and reinforcement.