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Samantha was three years old when her mom played a major scale for her on a used piano. Her mom sang the Do-Re-Mi song from The Sound of Music, providing Samantha's very first music training.
In the kitchen three days later with her mom, Samantha declared, “F…the oven is an F.”
It took a little while, but her mom realized that Samantha was talking about notes on the scale. Samantha’s mom went to the piano, played an “F”, and discovered that the hum of the microwave was an “F” (1).
Samantha, like the musicians above, possesses a trait called “absolute pitch” (AP) or “perfect pitch,” the ability to identify or produce a specific pitch of sound without a reference point. Like many children with this trait, Samantha can identify the pitch of appliances and sounds like a person blowing his nose.
The contributions of musical training and genetics in the development of absolute pitch are not well understood. Many studies suggest that both genetic factors and environmental factors, such as musical training early in childhood, contribute to the expression of the trait (2), although there is evidence that non-musicians can possess absolute pitch (3,4). As early as 1893, researchers described absolute pitch as an inborn ability (5). Scientists are interested in learning more about the phenomenon of absolute pitch (AP) because it may provide a model for other cognitive functions that are influenced by genetic environmental factors. Understanding AP may also give insight into how young children learn.
Pitch is defined as the number of vibrations per second produced by a sound source, such as wind rushing through a pipe. The ear is designed for frequency analysis, typically in the range of 20–5,000Hz, and most individuals can appreciate relative differences in frequency and timbre of a sound without any special training. AP does not require a “super” ear but instead requires a special ability to process and organize the information about sound that comes to the brain from the ear (6).
A normal individual can identify general ranges of pitch, six to eight fairly broad categories. However, to possess AP, a person must be able to form many fixed-pitch categories (70 or more; 7), and the person must be able to associate a verbal name with each of these many categories as well. The ability to create large numbers of “named” categories and store the information in the brain so that it is easily retrievable suggests that the differences that lead to absolute pitch perception are changes within the central nervous system where information coming from the ear is processed and organized. The sense of the biological definition for AP does not restrict “named categories” to the traditional note names used in Western music (A, B#, C, etc.). For the biological definition, “naming” means that a person can associate a mental tag or label to a given pitch; the brain recognizes and labels a pitch consistently without needing to compare it to any other pitch.
Are these changes in the nervous system genetic or a matter of environmental factors (such as music training) influencing development? Geneticists have determined that AP is not randomly distributed across worldwide populations (2). Asian populations tend to have a higher prevalence of AP, and this higher prevalence is even found in Asian Americans who often are primarily English speaking. Additionally the prevalence varies within different subgroups of the Asian population, and the variation does not appear to correlate with tonal languages (2).
In a study of more than 600 musicians, Baharloo and colleagues describe 4 distinct AP phenotypes, and each AP phenotype appeared to be consistent for the AP possessors of a given family lineage. Forty eight percent of people self-reporting AP also indicated that they had siblings, parents or children who also had AP (8). Analysis of the pedigrees of some of these families suggests that AP may be inherited as an incompletely penetrant, autosomal dominant trait (8). Further analysis indicated that the degree of risk for AP (the chance a sibling of a person with AP would also possess the trait) ranges from 8–15% (9), not terribly different from Schizophrenia, which has a clear genetic component and a degree of risk of 9%.
A few other pieces of evidence point to a genetic basis for AP, including the fact that congenital amusia, the inability to recognize pitch at all (absolutely or relatively), shows a higher incidence in identical than fraternal twins (2). Additionally AP has been reported anecdotally in cases of Williams-Beuren Syndrome as well as autism (6), although no molecular links have been described.
The Baharloo study concludes that, although AP does have a genetic component, its development is dependent on early musical training. They base this conclusion on the observation that 40% of musicians trained at age 4 or earlier reported AP compared to 3% of musicians who received their first training after age 9 (8). They conclude that early musical training is necessary but not sufficient for the development of AP; however, this does not address the reports of AP in non-musicians (1,4). Some studies link the development of a particular type of AP to learning tonal languages such as Vietnamese and Mandarin and suggest that these individuals develop the trait within the first year. They suggest that AP is universal in infancy, and that children who speak non-tonal languages develop the trait within the first year of life; otherwise AP only occurs in rare individuals for whom the critical period for acquiring the trait extends into early childhood (10).
Another study determined that individuals with AP identify some pitches more easily than others (11). Half-tones within the key of C major (flats and sharps) tend to be more difficult to identify, and possessors of AP in this study more easily recognized the eight tones of the C major scale. The author proposes that this is a result of early piano training being focused on the “white” keys of the piano and the C major scale (11). This hypothesis then argues that AP not only requires musical training, but that the type of musical training influences the nature of AP.
Many studies have indicated that the brain is plastic, capable of changing to compensate for injury or loss, and induced changes can occur within the auditory system (for review, 12). Structural and functional studies of the brains of musicians have demonstrated that the rigorous daily musical training of professional musicians can cause changes in the cerebral cortex, and the scope of these changes may depend on the age at which the musical training began (13–16). In the case of AP, studies indicate that musicians possessing AP have significant asymmetry between the right and left planum temporale (PT), a structure in the posterior part of the auditory cortex that has been linked to language, auditory processing and associative learning (17–19).
Keenan and colleagues demonstrate that musicians with AP show more leftward PT asymmetry than musicians who do not possess AP (19). These findings are consistent with studies conducted by other groups (16,17). The Keenan study suggests that the PT asymmetry, like early musical training, is a determinant of AP but that exposure to early musical training is not responsible for the development of this asymmetry. These authors also suggest that the asymmetry develops more as a function of pruning the right PT during development rather than enlarging the left PT.
Using positron emission topography (PET), Zatorre and colleagues measured cerebral blood flow in the brains of musicians with and without AP. Increased blood flow in a region of the brain indicates activity in that area (17). In their study, both groups showed increased blood flow in the cortical auditory areas when presented musical tones. The AP musicians showed increased blood flow in areas of the frontal cortex that are linked to associative learning (Figure 1, upper). This result suggests that AP musicians are associating a pitch with a verbal label. The non-AP musicians showed similar blood flow patterns only when they were asked to label intervals as major or minor (a relative pitch task; Figure 1, lower). In non-AP musicians, the group also detected increased blood flow in the inferior frontal cortex during presentation of musical tones. Similar blood flow patterns were not detected in the AP musicians. This finding may mean that the AP musicians were not accessing working memory when presented with the tones.
Figure 1. Averaged PET subtraction images are shown superimposed upon the averaged MRI scans for the tones-minus-noise subtraction (upper) and minor/major-minus-noise subtraction (lower) for listeners with AP (left) and control musicians—RP (right). Figure reprinted from reference 17. Copyright 1998. National Academy of Sciences, USA.
Functional MRI (fMRI) is also being used to look at areas of brain activity in AP and non-AP musicians. Like PET, fMRI shows blood flow in the brain over time and can reveal timing and places of activity in the brain. In a study involving six AP musicians from vastly different demographic backgrounds and a matched control group of non-AP musicians, Ross and colleagues determined that the AP musicians showed identical patterns of brain activation when asked to reproduce or name specific tones (20). None of the non-AP musicians showed these patterns of activation. Furthermore, in a study involving an AP musician who was also blind from early childhood, Ross and colleagues saw the same patterns of activation that had been described for the sighted AP musicians (21).
These functional studies indicate that AP is associated with specific processing pathways in the brain, but the precise cellular and molecular mechanisms for encoding absolute pitch are not understood. The genetic studies indicate a genetic predisposition for AP, even that AP may be inherited as an incompletely penetrant, autosomal dominant trait, although no specific genetic polymorphism has been shown to segregate with the trait. Studies of infants show that infants can track patterns of absolute pitches (22), and this contradicts a hypothesis that a rare genetic change is responsible for the development of AP. Perhaps the ability to track AP is inborn, and the genetic event responsible for the development of AP in individuals of Western populations is an event that extends the critical time period for developing AP into early childhood.
Like a dissonant musical piece, the story of AP does not conclude with a satisfying V-I cadence but instead ends on the Major 2nd, leaving many questions unanswered. Genetic studies of family pedigrees at the molecular level, larger scale population genetic studies and continued exploration of the central nervous system using realtime imaging techniques will eventually connect to give a more complete picture of the biology behind this complex phenomenon and resolve the dissonance.
While the final resolution of the dissonance regarding the “how” and “why” of AP may now elude us, the musical expression of the trait flourishes. Indeed our aforementioned 3-year old Samantha began at the same age as Mozart. Like Samantha, Wolfgang was a precocious, gifted child. And it was the clavier, an early keyboard instrument, that first attracted his ear.
Born in Salzburg in 1756, Wolfgang Amadeus Mozart (hereafter Mozart) was the seventh child of Leopold and Maria Mozart. In her memoirs, his older sister Nannerl wrote that she began studying clavier at age seven with their father, Leopold. “[The three-year old Wolfgang] at once showed his God-given [and] extraordinary talent. He often spent much time at the clavier, picking out thirds, which he was always striking, and his pleasure showed that it sounded good”(23,27).
By age four Mozart was learning small clavier compositions from the notebook compiled for his sister’s lessons. His first compositions were written at age five and recorded by his father. At six he taught himself to play the violin and insisted on joining in a rehearsal of a string ensemble at his home, stating that one did not need training to play second violin. Mozart gave his first musical performance in 1762, just before his sixth birthday; he and Nannerl played in Munich for the elector of Bavaria, Maximilian III Joseph. Over the next decade the children made five tours, performing for and winning the acclaim of nobles and music lovers throughout Europe (24).
Mozart was an extremely prolific and successful composer. Was his success the result of raw talent or hard work? Both, it seems. His letters from Vienna record a busy schedule filled with diligent effort at composing. He would awaken at six and work from seven until nine or ten. He taught lessons until one. When he was not performing, evenings found him again composing, often working until the wee hours of the morning (24,25).
The movie Amadeus made popular the stories of Mozart’s ability to conceive entire compositions in his mind and write them down perfectly. Modern scholars consider such stories part of the “Mozart myth.” Research has revealed that in the early stages of composition, Mozart used sketches and drafts and periodically threw them away. After his death, Constanze, his wife, “destroyed many” because of their “utter unusability.” Ulrich Konrad has discovered “that some 320 sketches and drafts survive, and that sketch material still exists for 10 percent of Mozart’s work. . . . There are few surviving ‘continuity sketches’… but Mozart often outlined substantial sections of major works in his usual manner – notating the main (top) line and the bass part, leaving the remainder to be filled in later on. Whereas in his earlier works he often completed the scoring of each section and then moved on to draft the next, in Vienna he developed the practice of fixing the outer voices of an entire movement before returning to fill in the inner voices” (24).
Mozart’s letters and the reminiscences of family and
friends paint a fascinating portrait of his method of
composing. Constanze recalled that Mozart
composed and transcribed simple pieces “as if he were
writing a letter” (23). In his own words:
“When I am, as it were, completely myself, entirely
alone, and of good cheer – say, traveling in a
carriage, or walking after a good meal, or during the night
when I cannot sleep; it is on such occasions that my ideas
flow best and most abundantly. . . . .
All this fires my soul, and, provided I am not disturbed, my subject enlarges itself, becomes methodized and defined, and the whole, though it be long, stands almost complete and finished in my mind, so that I can survey it, like a fine picture or a beautiful statue, at a glance. Nor do I hear in my imagination the parts successively, but I hear them, as it were, all at once. . . .
When I proceed to write down my ideas, I take out of the bag of my memory, if I may use that phrase, what has been previously collected into it. . . . the committing to paper is done quickly enough, for everything is, as I said before, already finished; and it rarely differs on paper from what it was in my imagination”(25).
Sketchbooks or no, no one would deny Mozart’s gift for composition or his tremendous capacity for musical memory. As a child, he astounded the nobles and court musicians of Europe with his ability to improvise. As an adult, he claimed to plan and compose pieces in the midst of other activity, even planning one piece while writing down another. He wrote to Nannerl, “I send you herewith a prelude and a three-part fugue [in C major, k.394]…I composed the fugue first and wrote it down while I was thinking out the prelude”(23).
The Mozart family was a musical one. With a recorded five generations of individuals with musical ability, the family tree offers some evidence that musical talent is genetically influenced. Mozart’s father, Leopold, who was responsible for his children’s academic and musical training, was a professional musician. Mozart’s maternal grandmother, Rosina Altman, was the daughter of a musician. His maternal grandfather, Wolfgang Nikolaus Pertl, a bureaucrat by profession, held a position as a singing instructor while pursuing his academic studies. Nannerl, Mozart’s older sister, was considered a child prodigy and performed on tour with her brother until age eighteen. Mozart was married to Constanze Weber, a singer and first cousin of composer Carl Maria von Weber. The couple had six children. Two sons lived to adulthood and both possessed musical ability. The younger, Franz Xaver Mozart, was a professional pianist and a composer (26,28–30).
AP is a gift that may sometimes seem a curse. AP is associated with specific changes in the brain, but do these changes have any drawbacks that affect other neurological processes? Certainly, history points to many truly gifted musicians with AP, but AP is not necessary for developing musical abilities and may even cause difficulty in performing some musical tasks. For example, individuals with AP may find it nearly impossible to listen to and enjoy even slightly out-of-tune voices or instruments. Healey Willan has said, “In music, absolute pitch is of relative importance, but relative pitch is of absolute importance” (26).
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