Absolute Pitch Implications for Pitch Coding, Perception, and Cognitive Development

1
Absolute PitchImplications for Pitch Coding,
Perception, and Cognitive Development

• Elissa Larkin and Zarin Mehta
• Arizona State University

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Introduction Absolute Pitch

• Absolute or perfect pitch is a rare,
  well-defined, and verifiable phenomenon of
  auditory perception
• Defined as the ability to either
• Identify the chroma (pitch class) of a tone
  presented in isolation or
• To produce a specified pitch without external
  reference (Parncutt Levine, 2001 Ross, et al.,
  2005)
• Incidence of absolute pitch 1 in 10,000 (Ward,
  1999)

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Introduction Absolute Pitch

• Absolute pitch (AP) is a two-step process that
  involves
• 1. Pitch memory
• 2. Pitch labeling
• People with AP automatically connect the memory
  of a pitch with a musical label
• Individuals with AP can label pitch the way most
  people label colors

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Introduction Absolute Pitch

• Pitch and color are, however, phenomenologically
  different
• Colors are experienced as belonging to categories
  while pitch is experienced by most humans as
  continuous
• Information from the peripheral auditory system
  is more continuous than the retina and lacks the
  one-to-one mapping between excitation patterns
  and percepts observed for the cones of the retina
• The fact that some individuals are able to place
  pitches into categories (an additional feature of
  pitch perception) raises the question of what is
  different about their neural development and
  architecture
• (Levitin Rogers, 2004)

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Absolute vs. Relative Pitch

• Absolute pitch (AP) must not be confused with
  relative pitch
• Relative pitch (RP) is
• An ability to identify intervals or pitches in
  relation to one another, rather than to recognize
  an exact frequency (tone height)
• In AP, a specified pitch is labeled or produced
  quickly accurately without any external
  reference (tone chroma)

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Relevance to Speech and Hearing

• Understanding AP may increase understanding of
  pitch perception, a critical element of auditory
  processing and language development
• AP may be an ideal phenotype to serve as a model
  for understanding cognitive functions that
  develop through complex interactions of neural
  structures, genes, and the environment
• AP shares traits identified in other
  developmental conditions whose causes remain
  under investigation
• For example
• Autism Spectrum Disorders (ASD)
• Specific Language Impairment (SLI)

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Common Misconceptions

• Possession of AP is a mark of musicianship
• FACT
• AP is largely irrelevant to most musical tasks
  (Corliss, 1973)
• The memory component of AP may, however, make
  specific tasks such as transcription easier
• You can teach yourself to have AP
• FACT
• Through rigorous training, people without AP can
  learn to label notes with better than chance
  accuracy
• But they do so with great effort never approach
  the close to 100 accuracy of AP possessors
  (Ward, 1999)
• AP can be activated at will
• FACT
• Individuals with AP cannot voluntarily turn off
  this phenomenon (Ross, et al., 2005)

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Brief History of Theories Regarding AP

• Formally defined and differentiated from relative
  pitch in a seminal work by Bachem (1937)
• Corliss (1973) was herself a possessor of AP and
  tried to define it further describing her own
  experience
• Original definitions were limited by the required
  ability to label musical pitches using Western
  nomenclature, thereby, excluding those trained in
  other traditions or not musically trained at all
• Tonotopic and inner hair cell temporal firing
  pattern theories of pitch encoding coincided with
  more recent AP research using neuroimaging
  techniques the possibility of distinct
  underlying neurobiological mechanisms is being
  considered (Ross, et al., 2005)

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Etiology

• The etiology of AP is controversial
• Two main theories proposed in the literature
  include
• AP as largely innate (genetic component)
  (Baharloo, et al., 2000 Gregerson, et al., 2000)
• AP as learned early in life through intensive
  musical training (environmental component)
  (Miyazaki, 1988 Takeuchi Hulse, 1993)
• Both theories, however, consider AP as an
  exclusively musical phenomenon
• Others contend that AP may be relatively
  independent of musical experience (Deutsch, 2002)
• Some suggest that there may be different types of
  AP determined by discrete neurobiological
  mechanisms (Ross, et al., 2005)

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Etiology

• Ross et al., (2005) proposed a new model based on
  the principles that
• AP may be relatively independent of musical
  experience
• There may be different types of APs that can be
  attributed to discrete neurobiological mechanisms
• For individuals with AP, pitch processing may
  involve lower level stimulus processing
• A phenomenon Ross et al., referred to as
  preattentive processing

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Theory of Preattentive Processing

• Individuals with AP may process pitch stimuli at
  a lower cognitive level
• In addition to communication of temporal
  information through phase locking
• Auditory systems of individuals with AP may
  contain a mechanism that translates the most
  frequently occurring spike intervals into
  specific place codes for pitch (Ross, et al.,
  2005)

(Campbell Greated, 1987)
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Theory of Preattentive Processing

• Ross et al., proposed that possessors of AP
  process the additional auditory feature of pitch
  chroma
• This information is processed at a lower level in
  the cognitive pathway and then transmitted to
  higher brainstem nuclei, bypassing intermediate
  (less accurate) processing mechanisms such as the
  periodotopic pathway

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Genetics Language Development AP More
than a Musical Phenomenon?

• Some researchers suggest all humans are born with
  capacity to acquire AP but need early musical
  training to express it (Saffran Griepentrog,
  2001)
• Others think that input does not need to be
  musical
• Speakers of two tonal languages, Vietnamese
  Mandarin, displayed extremely precise form of AP
  in enunciating words (Deutsch, 2002)
• AP may have evolved as a speech feature
  (analogous to other features, e.g. vowel quality)
• Infants may acquire this feature during 1st year
  of life when other speech features are acquired
• To date, there is no conclusive evidence that all
  infants are born with fixed pitch categories
  (Saffran Griepentrog, 2001 Zatorre, 2003)

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Genetic Component

• A twin study of four sets of twins found
• Three identical sets were concordant for AP
• The one dizygotic pair was not (Gregerson, 1998)
• About 25 of AP possessors have first-degree
  relatives with AP
• Suggesting an autosomal dominant inheritance
  pattern with incomplete penetrance (Baharloo, et
  al., 2000)
• Ethnic differences
• 40 greater prevalence of AP reported among
  Asians compared to Caucasian students (Gregerson,
  et al., 2000)

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Environmental Component

• Investigations of possible genetic links revealed
  that a great majority of AP possessors were
  exposed to musical training at an early age
  (Baharloo, et al., 2000 Gregerson, et al., 2000)
  
• Investigations comparing relative pitch training
  (e.g., most Western techniques) and non-relative
  tone labeling or do-re-mi techniques, (e.g.,
  Yamaha and Royal College) found that neither of
  the two types of input was more effective for AP
  development (Gregerson, et al., 2000)
• Association of pitches generally with linguistic
  meaning (e.g., tonal language) rather than with
  musical labeling also may be sufficient for AP
  development (Deutsch, 2002)

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Critical Development Period

• For speakers of non-tonal languages, AP
  development may be dependent on an unusually long
  critical period for acquisition (until music
  instruction begins) as compared to typical
  expectations for language feature acquisition
  (within 1st year of life) (Deutsch, 2002)
• In such cases, exposure to musical training
  appears to be critical for AP development but it
  must occur early in life (Miyazaki, 1988
  Takeuchi Hulse, 1993)
• About 40 of musicians who began training at lt 4
  years of age possessed AP (Baharloo, et al.,
  1998)
• Although attempts have been made, no adult has
  been able to acquire AP (Brady, 1970 Ross, et
  al., 2005)

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Not a Static skill Age-related Changes in AP

• Some individuals with AP reported musical
  paracusis
• Results of a study that combined a web-based
  survey and pitch-labeling test identified 981
  individuals with extraordinary pitch-naming
  ability showed (Athos, et al., 2007)
• Gradual decline in pitch-naming accuracy with age
• Decline was characterized by perceptual shift in
  the sharp direction (e.g., C sounds like a C
  sharp)
• Hypothesis (Athos, et al., 2007)
• Increase in basilar membrane elasticity caused
  displacement of the cochlear frequency map in the
  sharp direction
• Hair cells were resonating at a lower tone but
  still hard-wired to signal higher frequency
  recognition sites in the auditory cortex
• Tone was therefore perceived at a higher frequency

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Neurobiology Form

• Individuals with AP have smaller regions of the
• Right superior temporal cortex
• Right planum temporale (Keenan, et al., 2001
  Zatorre, 1998)
• Implications of this unique asymmetry have yet to
  be determined
• There may be complex interactions between
  anatomical feature size and function (Zatorre,
  2003)
• This finding may have implications for our
  understanding of neuroplasticity as it relates to
  auditory stimuli

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Neurobiology Form

• Planum temporale (PT)
• The PT is the cortical area just posterior to the
  auditory cortex (Heschls gyrus)
• A triangle-shaped region, its location is roughly
  consistent with Wernickes area
• The planum temporale typically shows a
  significant asymmetry
• Normally, in 65 of individuals the left PT
  appears to be more developed, while the right PT
  is more developed in only 10 of individuals
• This lateralized structure is involved with
  language and music

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Neurophysiology Function

• fMRI and PET studies performed during pitch
  processing tasks demonstrated (Zatorre, et al.,
  1998)
• Cerebral activity in individuals with AP that was
  distinct from individuals with RP as well as
  typical listeners
• Upon exposure to a single pitch, AP appeared to
  activate the posterior dorsolateral cortex, known
  for its involvement in conditional associational
  processing or labeling (i.e., long-term memory)
• RP only activated this area when labeling
  intervals
• In contrast to individuals with AP, musicians
  with RP responded to a single tone with increased
  activity in an area of the right frontal cortex
  that is known to participate in monitoring pitch
  information in working memory

Functional Magnetic Resonance Imaging and
Positron Emission Tomography
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Neurophysiology Function

• These differences lend credence to the notion
  that
• Individuals with AP store representations of
  individual pitches in their long-term memory
• And, therefore, do not use working memory to
  maintain tones or intervals as references for
  identification of each new tone heard (Zatorre et
  al., 1998).

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Shared Neurological Characteristics with ASD

• Atypical planum temporale (PT) asymmetry
• Although PT is found to have an asymmetry in the
  normal population, people who possess AP have an
  increased leftward asymmetry of the PT
• This finding is due to smaller than average
  volume of right PT and not larger than average
  volume of left PT
• Both children and adults diagnosed with ASD and
  adult musicians with AP demonstrate atypical
  volume differences between left and right PT
  (Rojas, et al., 2002 Rojas, et al., 2005
  Keenan, et al., 2001)
• Atypical PT asymmetry also has been reported in
  several other disorders associated with
  communication deficits, such as specific language
  impairment (SLI) (Gauger, et al., 1997)

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Shared Behavioral Characteristics Between AP and
ASD

• A tendency to focus on isolated features of a
  configuration, known as piecemeal information
  processing, is characteristic of ASD (Rimland,
  2003)
• AP is an extreme and rare example of piecemeal
  information processing
• A study associated musical tones with animal
  pictures as an analogy for AP and found
• Musically naïve children with ASD were better
  able to identify recall single notes than
  age-matched peers (Heaton, et al., 1998)

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Shared Behavioral Characteristics Between AP and
ASD

• In a study of musicians with AP (Brown, et al.,
  2003)
• A substantial proportion of subjects displayed
  deficits in social communication and behavior
  characteristics similar to the broad autism
  phenotype
• Brown, et al., concluded that gene(s) that
  underlie AP maybe among those that code for
  autism

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Future Research

• Studies to detect genetic similarities between
  individuals with AP
• Comparative studies of input types (musical
  labels vs. tonal language meanings) to determine
  if both are effective environmental components
  for AP development
• If different types of input can lead to AP, does
  each have a different critical period for
  development?
• Studies to assess connections between AP and
  other populations of interest may yield
  meaningful clinical information
• For example, auditory processing and memory
  activation patterns in AP compared to ASD and SLI
• Additional research is needed to determine if
  distinct types of AP exist as current theories
  suggest