杏吧原创

ELIZABETH WEST MARVIN can always tell which music students have perfect
pitch. They don鈥檛 necessarily play any differently from her other students, and
they may not always lead the chorus. But they are the ones who immediately get
distracted when the fluorescent lights above their heads start vibrating with an
electrical hum somewhere between B and B-flat.

The uncanny, if sometimes distracting, ability to name a solitary note out of
the blue, without any other notes for reference, is a prized musical
talent鈥攁nd a scientific mystery. Musicians with perfect pitch鈥攐r, as
many researchers prefer to call it, absolute pitch鈥攃an often play pieces
by ear, and many can transcribe music brilliantly. That鈥檚 because they perceive
the position of a note in the musical stave鈥攊ts pitch鈥攁s clearly as
the fact that they heard it. Hearing and naming the pitch go hand in hand.

By contrast, most musicians follow not the notes, but the relationships
between them. They may easily recognise two notes as being a certain number of
tones apart, but could name the higher note as an E only if they are told the
lower one is a C, for example. This is relative pitch. Useful, but much less
mysterious.

For centuries, absolute pitch has been thought of as the preserve of the
musical elite. Some estimates suggest that maybe fewer than 1 in 2000 people
possess it. But a growing number of studies, from speech experiments to brain
scans, are now suggesting that a knack for absolute pitch may be far more
common, and more varied, than previously thought. 鈥淎bsolute pitch is not an all
or nothing feature,鈥� says Marvin, a music theorist at the University of
Rochester in New York state. Some researchers even claim that we could all
develop the skill, regardless of our musical talents. And their work may finally
settle a decades-old debate about whether absolute pitch depends on melodious
genes鈥攐r early music lessons.

Music psychologist Diana Deutsch at the University of California in San Diego
is the leading voice. Last month at the Acoustical Society of America meeting in
Columbus, Ohio, Deutsch reported a study that suggests we all have the potential
to acquire absolute pitch鈥攁nd that speakers of tone languages use it every
day. A third of the world鈥檚 population鈥攃hiefly people in Asia and
Africa鈥攕peak tone languages, in which a word鈥檚 meaning can vary depending
on the pitch a speaker uses.

Deutsch and her colleagues asked seven native Vietnamese speakers and 15
native Mandarin speakers to read out lists of words on different days. The
chosen words spanned a range of pitches, to force the speakers to raise and
lower their voices considerably. By recording these recited lists and taking the
average pitch for each whole word, the researchers compared the pitches used by
each person to say each word on different days.

Both groups showed strikingly consistent pitch for any given word鈥攐ften
less than a quarter-tone difference between days. 鈥淭he similarity,鈥� Deutsch
says, 鈥渋s mind-boggling.鈥� It鈥檚 also, she says, a real example of absolute pitch.
As babies, the speakers learnt to associate certain pitches with meaningful
words鈥攋ust as a musician labels one tone A and another B鈥攁nd they
demonstrate this precise use of pitch regardless of whether or not they have had
any musical training, she adds.

Deutsch isn鈥檛 the only researcher turning up everyday evidence of absolute
pitch. At least three other experiments have found that people can launch into
familiar songs at or very near the correct pitches. Some researchers have
nicknamed this ability 鈥渁bsolute memory鈥�, and they say it pops up in other
senses, too. In a 1994 study, for example, Svein Magnussen and Stein Dyrnes of
the University of Oslo in Norway found an absolute memory for visual images,
showing that people could pick out complex black-and-white line designs they had
seen hours or days earlier from a selection of very similar ones.

Given studies like these, the real mystery is why we don鈥檛 all have absolute
pitch, says cognitive psychologist Daniel Levitin of McGill University in
Montreal. 鈥淚 don鈥檛 have to run to a rainbow and find red to tell you that a
tomato is red,鈥� Levitin says. 鈥淭here are 10 basic colours that everyone can name
immediately. Well, there are 12 basic pitches. If we can label all those
colours, why can鈥檛 we label all those pitches?鈥�

Levitin suspects he knows the answer. Absolute pitch, he says, is really a
two-step process: pitch memory and pitch labelling. It鈥檚 not that people with
absolute pitch are genetically endowed with a keener sense of pitch perception,
Levitin says鈥攁fter all, many of us can recall a note nearly perfectly
immediately after we hear it. But people with absolute pitch automatically
connect the memory of a pitch with a label. Some even describe different pitches
as having distinct 鈥渃olours鈥� or 鈥渃haracters鈥�.

Lacking absolute pitch, most of us can鈥檛 make that connection鈥攍abelling
a note as 鈥淒鈥�, for example. But do the connections and labels get hammered in
during music lessons, or are some babies just born with a flair for identifying
pitch? That鈥檚 a hard question to answer, since musical parents often pass a
passion for music鈥攁s well as their genes鈥攐n to their children.

Over the past decade, researchers have confirmed that absolute pitch often
runs in families. Nelson Freimer of the University of California in San
Francisco, for example, is just completing a study that he says strongly
suggests the right genes help create this brand of musical genius. Freimer gave
tone tests to people with absolute pitch and to their relatives. He also tested
several hundred other people who had taken early music lessons. He found that
relatives of people with absolute pitch were far more likely to develop the
skill than people who simply had the music lessons. 鈥淭here is clearly a familial
aggregation of absolute pitch,鈥� Freimer says.

Blossoming talent

Freimer says some children are probably genetically predisposed toward
absolute pitch鈥攁nd this innate inclination blossoms during childhood music
lessons. Indeed, many researchers now point to this harmony of nature and
nurture to explain why musicians with absolute pitch show different levels of
the talent. 鈥淭he early learning period鈥攆rom about three to six years of
age鈥攊s critical,鈥� says Marvin. But lucky genes probably help, she
adds.

Indeed, researchers are finding more and more evidence suggesting music
lessons are critical to the development of absolute pitch. In a survey of 2700
students in American music conservatories and college programmes, New York
University geneticist Peter Gregersen and his colleagues found that a whopping
32 per cent of the Asian students reported having absolute pitch, compared with
just 7 per cent of non-Asian students. While that might suggest a genetic
tendency towards absolute pitch in the Asian population, Gregersen says that the
type and timing of music lessons probably explains much of the difference.

For one thing, those with absolute pitch started lessons, on average, when
they were five years old, while those without absolute pitch started around the
age of eight. Moreover, adds Gregersen, the type of music lessons favoured in
Asia, and by many of the Asian families in his study, such as the Suzuki method,
often focus on playing by ear and learning the names of musical notes, while
those more commonly used in the US tend to emphasise learning scales in a
relative pitch way. In Japanese preschool music programmes, he says, children
often have to listen to notes played on a piano and hold up a coloured flag to
signal the pitch. 鈥淭here鈥檚 a distinct cultural difference,鈥� he says.

If the right genes and music lessons do prompt people to label tones in a
fundamentally different way, then this cognitive difference should show up in
their brains. As indeed it does. In a 1998 study, neuroscientist Robert Zatorre
of the Montreal Neurological Institute in Canada ran positron emission
tomography (PET) scans of musicians with and without absolute pitch while they
listened to tones.

When asked to label a tone, the musicians lacking absolute pitch had a flash
of brain activity in the right frontal cortex鈥攁n area associated with
working memory and comparing incoming sensory information with memories. By
contrast, the musicians who had absolute pitch could identify tones without
accessing working memory at all. Instead, they showed a spark of brain activity
high in the left frontal cortex鈥攁 region related to long-term memory.
Zattore suggests that the absolute pitch users were tapping into a more deeply
ingrained pitch template that they developed during childhood lessons.

A study led by musicologist Laura Bischoff of Shepherd College in West
Virginia also shows that people with the strongest absolute pitch skills can
name notes without working memory. Bischoff and her colleagues gave 32 music
students鈥攈alf of whom had absolute pitch鈥攁 series of tone tests
while the students wore a jumble of scalp electrodes. The researchers were
looking for a working memory marker: the P300, a positively charged waveform
that flashes across the brain 300 milliseconds after a surprising stimulus. The
P300 is thought to indicate a comparison of incoming sensory stimuli鈥攕uch
as a new tone鈥攚ith memorised information, in this case a musical
scale.

During one test, the students listened to a typical scale, trying to guess
whether the note being played fitted within the scale. At first, the notes would
build predictably, neatly forming a scale in the key of C. But then a tone would
jump out of scale, falling unexpectedly flat or sharp. Scrambling to name that
errant tone, the students without absolute pitch showed a P300 surge, as
expected, while most of the students that had absolute pitch did not.

But the experiment also showed how varied a talent absolute pitch can be.
Four of Bischoff鈥檚 absolute pitch students showed brain wave patterns more like
those in the control group. Further tests revealed that these absolute pitch
students alternated between absolute and relative pitch, depending on the task
at hand.

The lesson, Bischoff says, is that absolute pitch is not a one-size-fits-all
talent. Some people have an acute sense of absolute pitch, while others show
just a hint of the skill. And some absolute pitch possessors use it only
occasionally, flipping back to relative pitch when that skill is more
useful.

A bit of both

That doesn鈥檛 surprise Philip Chang, a music theory graduate student at
Rochester. While he鈥檚 had absolute pitch since he was a child, Chang has also
had training that hones relative pitch skills鈥攑ractising scales,
recognising intervals and so on. 鈥淚 just use what鈥檚 helpful,鈥� he says.

But can anyone develop absolute pitch? Bischoff thinks so. 鈥淥ur studies tie
right in with the idea that we all have this latent absolute pitch ability, but
we can鈥檛 get fully bloomed absolute pitch without early childhood training,鈥�
says Bischoff.

But some scientists are more cautious. After all, if everyone remembered
pitches, but just couldn鈥檛 label them, we鈥檇 immediately know if something was
played in an unusual key, or if two songs started on the same note, says
psychologist Andrea Halpern of Bucknell University in Lewisburg, Pennsylvania.
These feats, she says, are reserved for people with absolute pitch.

Similarly, linguists are wary of the idea that consistently speaking in a
given pitch range somehow reflects absolute pitch. People naturally settle into
a comfortable range while talking, says Rebecca Herman, a linguist at Indiana
University. Deutsch counters that this 鈥渃omfort zone鈥� argument can鈥檛 explain the
exceedingly small differences in pitch among her speakers.

Indeed, Deutsch predicts that further studies will reveal absolute
pitch鈥攊n its imperfect, latent form鈥攊nside all of us. The Western
emphasis on relative pitch simply obscures it, she contends. 鈥淚t鈥檚 very likely
that scientists will end up concluding that we鈥檙e all born with the potential to
acquire very fine-grained absolute pitch. It鈥檚 really just a matter of life
getting in the way.鈥�

Humans may have to search high and low for traces of absolute pitch, but
other animals flaunt the talent. Researchers have found that bats, wolves,
gerbils and birds all sometimes use forms of absolute pitch to spot possible
mates鈥攐r meals鈥攁mid nature鈥檚 cacophony.

Songbirds, in particular, put humans to shame. In a 1998 study, psychologist
Ron Weisman at Queen鈥檚 University in Ontario, Canada, pitted 10 male zebra
finches against 10 accomplished musicians. The birds had to decide whether to
fly to a feeder that opened only when tones within four narrow frequency ranges
were played, while the humans pushed a button to indicate whether a pitch was in
one of the designated ranges鈥攁nd won prize money for correct answers.

Towards the end of the experiment, Weisman says, the feathered participants
identified pitch correctly 85 per cent of the time, while our species succeeded
just over half the time. 鈥淲e didn鈥檛 have the heart to tell these skilled
musicians that their performance was abysmal compared to a bunch of birds,鈥� says
Weisman.

But there鈥檚 good reason for these creatures鈥� virtuoso performances: zebra
finches recognise members of their own species by the pitch range of their
songs. 鈥淎nd if you鈥檝e ever heard birds in a dawn chorus, you know how hard it is
to distinguish one bird among the crowd,鈥� says Weisman. Zebra finches can
identify the absolute pitch of a mate鈥檚 song up to 100 metres away, he says.

Songbirds and songwriters do have some things in common, though. Both birds
and humans with absolute pitch can often switch to relative pitch as well,
Weisman says. What鈥檚 more, the birds hone their ear for pitch during youth, when
they listen for the calls of family members and neighbours. There are some music
lessons, Weisman notes, that really pay off.