Rhythm, Timbre and Hyperacusis in Williams-Beuren Syndrome

Rhythm, Timbre and Hyperacusis in Williams-Beuren Syndrome
Daniel J. Levitin
Departments of Psychology and Music Theory
McGill University, Montreal, QC CANADA
Ursula Bellugi
Salk Institute for Biological Studies
La Jolla, CA
To appear in:
C. Morris, H. Lenhoff, and P. Wang (Eds)., Williams-Beuren Syndrome: Research and
Clinical Perspectives. Baltimore, MD: Johns Hopkins University Press.
Address correspondence to:
Daniel Levitin
Dept. of Psychology
McGill University
1205 Avenue Penfield
Montreal, QC H3A 1B1 CANADA
Phone: (514) 398-8263
Fax: (514) 398-4896
email: daniel.levitin@mcgill.ca

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Levitin & Bellugi
OUTLINE
1. Introduction
2. Rhythm
a. Rhythm production
b. Rhythm perception
3. Timbre Perception and Hyperacusis
a. Aversion
b. Attraction and auditory fascinations
c. Timbral identification
4. Neuroanatomical studies
a. Event-related brain potentials (ERPs)
b. Neuroimaging
c. Cytoarchitectonics
5. Clinical Implications
6. Projections for the next 5 - 10 years of research
7. Conclusions
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1. Introduction
Anecdotal reports have long suggested that individuals with WBS are especially
musical. Recent research has attempted to quantify and better understand the nature
and extent of these reported musical abilities in WBS, in an effort to enhance our
understanding of the relation among genes, development, brain and cognitive function.
This chapter reports on the extant literature concerning three of the phenotypic markers
of auditory and musical function in WBS – rhythmic ability (both production and
perception), timbre perception and memory, and hyperacusis. Rhythm, along with
pitch, is one of the two dissociable attributes of music (Krumhansl, 2000; Levitin, 2002)
and is fundamentally important in distinguishing one musical piece from another.
Controlled experiments have been conducted comparing the rhythmic abilities in
individuals with WBS to those of typically developing normal controls, as well as to
individuals with Down syndrome (DNS) and Autism. The research on timbre
perception has led to both behavioural and neuroimaging research that is reported here.
The term "hyperacusis" – an unusual sensitivity to sound – has an unfortunate history
of inconsistency of use in both the clinical and research communities; as will be shown,
it has been used to describe four vastly different auditory disorders and we attempt
here to clarify and reconcile these reports. Finally, the chapter will end with a section
on clinical implications and projections for future research.
At the outset, the most important observation to stress is that the WBS
individuals comprise a heterogeneous group with respect to musical ability and
achievement. That is, there is as much individual difference in this population as there
is in a normal population, and it would be inaccurate to claim that all individuals with
WBS are "musical." What can be said is that they are more likely to express love for
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music, to engage in musical activities (either creative or receptive) and to have longer
lasting emotional reactions to music (Don, Schellenberg & Rourke, 1999; Levitin &
Bellugi, in preparation).
2. Rhythm.
Rhythm is that aspect of music that encodes the temporal components of a
musical piece. In Beethoven's Fifth Symphony, for example, the opening phrase
consists of four notes played in a rhythm of short-short-short-long (bum-bum-bum-
baaaah). If this rhythmic phrase is inverted to long-short-short-short, the piece becomes
unrecognizable and has a completely different semantic meaning (Levitin & Menon,
submitted).
a. Rhythm production.
Levitin and Bellugi (1998) investigated the rhythmic abilities of individuals with
WBS, and examined rhythm production and memory. Using a series of rhythmic
patterns of increasing complexity, we engaged participants in an echo clapping task to
assess their mental representations of musical rhythms, and their ability to reproduce
them. In this task, the experimenter would clap a rhythm and the participant's task was
to clap that rhythm back as accurately as possible. The patterns were based on those
used in the Gordon Musical Aptitude Profile (Gordon, 1965/1995) and by Bruscia (1981)
in a similar paradigm, and provided a wide variety of temporal ratios.
The age of the WBS participants ranged from 9 - 20 (mean 13.4, s.d. 3.6); there
were two female and six male participants. To provide a comparison with mental-age
matched typically developing children, eight young normal participants were recruited
from Palo Alto, California, June 1997, two female and six male, with chronological age
ranging from 5 - 7, two participants for each age category. Because the WBS
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participants may have had a greater number of hours of musical exposure due to their
greater chronological age, we attempted to balance this by recruiting educationally
sophisticated young normal children who had taken at least three years of continuous
formal musical instruction, were from one of the highest rated school districts in
California, and were currently studying music privately.
Even though not specifically instructed to do so, the WBS participants in this
experiment (more so than the control participants) tended to look the experimenter in
the eye, rather than watching the experimenter's hands during the presentation of the
examples. This tendency toward eye contact was first documented in the documentary
film "Williams Syndrome - A highly musical species" (Wilmowski, 1995)by the drum
instructor K. B. McConnel. Also, on nearly every trial, the WBS participants clapped
back the rhythms immediately in perfect time, without missing a beat, as if their
response formed part of the same rhythmic sequence. That is, when the experimenter
was finished giving the exemplar, the participants came right in on the next beat
without pausing. All of the WBS participants thus appeared to interpret the examples
as forming part of a larger musical set; they acted as though they understood there to be
an implied time signature and tempo, and they responded to the "first measure" of
music played by the experimenter in time for the downbeat (or in some cases pickups)
to the "second measure." Moreover, the WBS participants revealed a remarkable ability
to track changes in rhythmic pulse, including changes to swing time, straight eighths,
triplets, sixteenths, syncopations, and so on. In some cases, the experimenter began the
next trial without pausing after the participants' response, giving the experimental
session the flavor of a jazz "jam" session of "trading ones," the technical term used to
describe musicians who alternate playing measures of a musical phrase.
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Quite surprisingly, we found that the WBS people performed as well as mental-
age matched controls. Most interestingly, on the one-third of the trials in which the
individuals with WBS made errors, the errors they made were far more likely to be
musically coherent than those of the controls. Put another way, their errors were
musical, as if completing the rhythmic phrase they were attempting to reproduce. This
finding was especially interesting as it stands in contradiction to Miller's (1989) position
that musical savants tend to lack rhythmic ability. In addition, Serafine (1979) had
argued that metric conservation in normal children is correlated with the standard
Piagetian conservation tasks; since most WBS individuals do not reach this Piagetian
stage (Bellugi, Wang, and Jernigan, 1994) and yet demonstrated conservation of musical
time, their performance is especially surprising and challenge important theoretical
models of cognitive abilities that couple these two forms of conservation. This study
concluded by suggesting that participants with WBS had evidenced a quality we called
rhythmicity or rhythmic musicality.
b. Rhythm perception.
In contrast to the just-mentioned experiment on rhythmic production, four other
studies have examined rhythmic perception.
Don, et al. (1999), Hopyan, et al. (2001) and Levitin & Bellugi (in preparation) all
administered the Gordon Primary Measures of Musical Audiation (PMMA), a standard
rhythm perception test (Gordon, 1986). The test is furnished on cassette tape, and
participants listen to pairs of examples that consist of short rhythmic phrases that are
either identical or slightly different; participants are to respond "same" or "different."
Don compared 19 individuals with WBS (mean age 10.5 years, s.d. 1.83; range 8 - 13) to
19 typically developing normal participants (mean age 7.9 years, s.d. 2.3, range not
given), matched for their levels of general cognitive ability (as indexed by the Peabody
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Picture Vocabulary Test-Revised, the PPVT-R). The control group performed better
than the WBS group on the rhythm sub-component of the PMMA, but the statistical
analyses employed subject to question, and therefore it is difficult to draw a firm
conclusion as to whether the differences are statistically significant or not. Don, et al.
apparently made multiple post-hoc comparisons without appropriate adjustments in
significance level, and failed to report the main effect of group in their analysis of
variance statistic.
Hopyan, et al. administered the same test to 14 children with WBS (mean age 12,
s.d. 3) and 14 chronologically-aged matched controls (mean age 12, s.d. 3). This study
reported that the control group performed significantly better than the WBS group on
the rhythm test. In our own laboratory, in an experiment currently underway, we
obtained the same results as Hopyan. But the pattern of errors made by the WBS
participants alerted us to a potential confound with the stimulus materials. More often
than not, our WBS participants were labeling "different" pairs of examples which the
PMMA had intended to be the same. On closer listening to the examples, we
discovered that the cassette tapes contained numerous rhythmic confounds, rendering
the rhythmic task more difficult to complete for a careful listener. Specifically, the test
as furnished by the manufacturer contains random static and recording artifacts that
create unintended spaces and gaps during long tones of the rhythm test. Thus, a
reference rhythm and its matched comparison rhythm may in fact appear different to a
careful listener when intended to be the same by the test maker. To remove this
potential confound from the experiment, we resynthesized and rerecorded all of the
examples digitally and administered the test to a fresh group of participants.
The participants performed very well on this resynthesized version. In order to
give the comparison group the best possible chance of performing better than our WBS
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group – in an effort to replicate the findings of Hopyan of better rhythm performance
among the controls – our control group were not simply matched on chronological age,
but were drawn from a pool of true musical experts – students at Julliard School of
Music in New York. In this work (currently in preparation) we found that WBS and
Julliard students performed equivalently on the rhythm tests, evidence that the WBS
group were performing significantly above their overall cognitive level and indeed on a
par with chronologically age-matched controls.
Brochard et al. (in press) tested rhythmic sequence discrimination employing a
same/different task in which the "different" examples differed either in meter or gestalt
grouping. Although the 9 WBS adults performed more poorly overall than 9 control
(matched for sex and chronological age), the WBS individuals showed a relative
strength in perceiving the metric rather than the grouping examples. Moreover, the
processing of rhythmic pauses was highly disturbed when some musical semantic
content was present.
Thus, with the exception of specific impairments on metrical sequences and
semantic pauses documented by Brochard et al. (in press), we would argue that both
rhythm production and rhythm perception are relative strengths in WBS, when bias-
free tests are used. Preliminary studies suggest a neuroanatomical basis for this relative
sparing of rhythmic ability, which will be discussed below. The most direct implication
of this finding is that caregivers may want to encourage individuals with WBS to play
rhythm instruments (percussion, drums, etc.) as a musical outlet. Indeed, a large
number of the males at the WBS music camp where we made our observations (Belvoir
Terrace) play the drums at a relatively proficient level, and play in small bands.
3. Timbre perception and hyperacusis
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It has been noted previously that individuals with WBS tend to be unusually
sensitive to and interested in sound (Udwin, 1990), a characteristic dubbed "soundscape
sensitivity" (Levitin and Bellugi, 1998) and often referred to by the medical term
"hyperacusis." Because the sensitivity to sound experienced by most WBS appears to be
related to specific tonal colors or timbres of those sounds, these two topics will be dealt
with in a single section.
The medical definition of hyperacusis is that it is an "abnormal sensitivity to
sound" (Dirckx, 2001; Venes, Thomas, & Taber, 2001) and indicates lowered hearing
thresholds (an ability to hear soft sounds that others cannot), but this description does
not adequately capture the phenomenology of WBS. Whereas there have been many
anecdotal accounts of WBS with lowered hearing thresholds (a claim not yet supported
by our own research), three unusual behaviours have additionally been reported in
WBS:
(i) Aversion to certain types of normal-volume sounds (Morelock and Feldman,
2000), commonly lawnmowers, leaf blowers, or vacuum cleaners, although the
particular sounds seem to be idiosyncratic from person to person, and there are many
others. The individuals' distress extends even to the anticipation of such noises
(Hagerman, 1999), and typical reactions to these noises are for children to put their
hands over their ears and cry, or attempt to avoid the source of the sound (Udwin,
1990). The aversion does not arise due to the loudness of the sounds, but to some
quality of them that has yet to be completely characterized. Because this shares a
conceptual similarity with allodynia, a pathological state typically following tissue or
nerve damage in which patients feel pain from stimuli that are not normally perceived
as painful, we propose to call this auditory allodynia (first suggested in Levitin, et al.
2003. These symptoms have sometimes been referred to in the literature as
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"phonophobia," but that term, like "hyperacusis" also has a history of misuse, and
consequently we opted for a new term without prior ambiguous associations).
(ii) Sounds that are not too loud for others are perceived as painfully loud to
them; this is essentially a lowered uncomfortable loudness threshold (LULL) and is not
necessarily related to a lowered hearing threshold, and should be referred to by the
term odynacusis (Dirckx, 2001; Venes, Thomas, & Taber, 2001). This is distinct from (i)
because individuals with LULLs react negatively to any sound beyond a certain level,
not only to particular sounds that they find idiosyncratically aversive.
(iii) intense fascination for certain classes of sounds, often the same sounds of
which they were frightened at a younger age (Levitin, Cole, Lincoln Bellugi, submitted).
The literature has tended to lump these behaviours together, using the single
term hyperacusis somewhat indiscriminately to describe these phenomena (Katznell &
Segal, 2001; Klein et al., 1990; Marriage, 1995; Phillips & Carr, 1998). Because these
symptoms stem from different underlying physiological correlates and etiologies, it is
important to be precise with terms so as not to lead to confusion. Klein, et al. (1990) for
example, used the term hyperacusis to describe our category #2 above – cases of
individuals with WBS who experienced "consistently exaggerated or inappropriate
responses or complaints of uncomfortable loudness to sounds that are neither
intrinsically threatening nor uncomfortably loud to a typical person. . . these responses
would occur on nearly every occasion that the sounds are presented and do not
habituate with repeated exposures" (p. 339). Hopyan, et al. (2001) use the term to mean
simply "an abnormally strong affective response to certain categories of sounds" (p. 42).
a. Aversion: auditory allodynia

Recently we have had the opportunity to refine our understanding of auditory
sensitivities in WBS through a questionnaire administered to 120 individuals with WBS
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