J Am Acad Audiol 17:487–497 (2006)
*Volen National Center for Complex Systems, Brandeis University; †Department of Otolaryngology, Boston University
School of Medicine; ‡Currently at the University of British Columbia
Dr. Arthur Wingfield, Volen National Center for Complex Systems (MS 013), Brandeis University, Waltham, MA 02454-
9110; Phone: 781-736-3270; Fax: 781-736-3275; E-mail: Wingfield@brandeis.edu
This work was supported by NIH grant AG19714 from the National Institute on Aging. We also gratefully acknowledge
support from the W.M. Keck Foundation.
Effects of Adult Aging and Hearing Loss on
Comprehension of Rapid Speech Varying in
Syntactic Complexity
Arthur Wingfield*
Sandra L. McCoy*‡
Jonathan E. Peelle*
Patricia A. Tun*
L. Clarke Cox†
Abstract
Comprehension of spoken language by older adults depends not only on
effects of hearing acuity and age-related cognitive change but also on
characteristics of the message, such as syntactic complexity and presentation
rate. When younger and older adults with clinically normal hearing and with
mild-to-moderate hearing loss were tested on comprehension of short spoken
sentences that varied in syntactic complexity, minimal effects of age and
hearing were seen in comprehension of syntactically simpler sentences, even
at rapid speech rates. By contrast, both age and hearing loss were associated
with poorer comprehension for more syntactically complex sentences, and these
differences were further exacerbated by increases in speech rate. These
findings illustrate a dynamic interaction between age, hearing acuity, and
characteristics of the spoken message on speech comprehension.
Key Words: Aging, hearing loss, speech comprehension, speech rate, syntactic
complexity
Abbreviations: DPOAE = distortion-product otoacoustic emission; fMRI =
functional magnetic resonance imaging; MCL = most comfortable listening level;
PET = positron emission tomography; PTA = pure-tone average; wpm = words
per minute
Sumario
La comprensión del lenguaje hablado en adultos mayores depende no sólo
de los efectos de la agudeza auditiva y de los cambios cognitivos relacionados
con la edad, sino también de las características del mensaje, tales como la
complejidad sintáctica y la velocidad de presentación. Cuando adultos jóvenes
y viejos con audición normal o con hipoacusias leves a moderadas, fueron
evaluados en cuanto a la comprensión de frases cortas habladas que variaban
en su complejidad sintáctica, se vieron mínimos efectos relacionados con la
audición o la edad, en el manejo de la oraciones de mayor simpleza sintáctica,
aún a velocidades rápidas del habla. En contraste, tanto la edad como la
hipoacusia se asociaron con una comprensión más pobre para frases
sintácticamente más complejas, y dichas diferencias se exacerbaron aún
más conforme aumentó la velocidad del habla. Estos hallazgos ilustran una
interacción dinámica para la comprensión del lenguaje, entre la edad, la
agudeza auditiva, y las características del mensaje hablado.
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Journal of the American Academy of Audiology/Volume 17, Number 7, 2006
488
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n spite of its seemingly automatic nature,
the comprehension of everyday speech
challenges our perceptual and cognitive
systems on a number of levels. One of these is
the rate at which speech arrives. While speech
in thoughtful conversation may be as “slow” as
90 words per minute (wpm), average speech
rates in ordinary conversation vary between
140 and 180 wpm, and a radio or television
newsreader working from a prepared script can
easily exceed 210 wpm (Stine et al, 1990). In
addition to low-level processing of this rapidly
changing acoustic signal, speech comprehension
regularly requires the involvement of higher-
level cognitive processes. Natural speech is
often underarticulated to the degree that many
words in fluent discourse would be completely
unintelligible were it not for listeners’ ability
to rapidly factor in the surrounding linguistic
context (Pollack and Pickett, 1963; Hunnicutt,
1985; Lindblom et al, 1992; Wingfield et al,
1994). The sentences in spoken discourse are
also not necessarily delivered in a simple
canonical form with uncomplicated syntax.
These challenges can create special
difficulty for older adults. An important issue
is the frequent occurrence of an age-associated
decline in peripheral and central auditory
processing capabilities that can significantly
affect the perception of speech (Humes, 1996;
Morrell et al, 1996). This is especially so when
the speech is rapid, degraded, or heard in noise
(Schneider and Pichora-Fuller, 2000). In
addition to these sensory changes, however, a
general slowing of perceptual and cognitive
operations and reductions in working memory
capacity are also hallmarks of the aging process
(Wingfield et al, 1988; Kausler, 1994; Salthouse,
1994, 1996). (“Working memory” refers to the
ability to hold and manipulate information in
immediate memory [Just and Carpenter, 1992;
Baddeley, 1996].)
The former factor (perceptual and cognitive
slowing) contributes to older adults’ well-known
difficulty with especially rapid speech (Sticht
and Gray, 1969; Konkle et al, 1977; Letowski
and Poch, 1996; Wingfield, 1996; Gordon-Salant
and Fitzgibbons, 1997), and the latter factor (a
decline in working memory efficacy) contributes
to older adults’ greater difficulty with
deconstructing syntactically complex speech
(Davis and Ball, 1989, Kemper, 1992; Kemtes
and Kemper, 1997). Indeed, when older adults
are subjected to rapid speech with complex
syntax, the combined effects on spoken sentence
comprehension have been shown to be
multiplicative (Wingfield et al, 2003).
Because linguistic knowledge and the
procedural rules for its application are well
preserved in older adulthood (see Wingfield
and Stine-Morrow, 2000, for a review), older
adults’ difficulties with single word
identification can be significantly reduced when
these words are heard in a sentence context
(e.g., Wingfield et al, 1991; Pichora-Fuller et al,
1995; Gordon-Salant and Fitzgibbons, 1997;
Dubno et al, 2000). On the negative side,
however, audiometric testing for speech can also
underestimate the effects of age and hearing
loss when listeners are confronted by speech
with cognitively demanding syntactic
structures, as often happens in everyday life.
This may be one of the number of reasons why
formal audiometric testing does not always
correlate with older adults’ everyday listening
experience.
To understand the cognitive burden
syntactic complexity can impose for successful
comprehension of even short sentences,
consider a syntactically simple sentence
consisting of two clauses connected by the
conditional “when.” An example might be,
“Boys are caring when they help girls.” As the
sentence unfolds in time, one processes the
first clause, “boys are caring,” then the
modifying clause, “when they help girls,” and
then integrates the two to give the full sentence
its meaning.
Occasionally, however, one can encounter
a sentence with the meaning expressed in the
form of an abbreviated but still relatively
simple structure using a center-embedded
clause. Such a sentence, referred to as a subject-
relative center-embedded clause sentence
Palabras Clave: Envej cimiento, hipoacusia, comprensión del lenguaje,
velocidad del habla, complejidad sintáctica
Abreviaturas:DPOAE = emisión otoacústica por producto de distorsión; fMRI
= imágenes por resonancia magnética funcional; MCL = umbral de escucha
más confortable; PET = tomografía por emisión de positrones; PTA = promedio
tonal puro; wpm = palabras por minuto