Page 10 - Fall 2007

AUDITORY AND AUDIOVISUAL SPEECH PERCEPTION IN CHILDREN WITH AUTISM SPECTRUM DISORDERS
Julia R. Irwin
Haskins Laboratories
New Haven, Connecticut 06511
Autism Spectrum Disorders
(ASD) are neurodevelopmental
disorders along a continuum of
severity that are generally character-
ized by marked deficits in social and
communicative functioning (American
Psychiatric Association, 2000).
Whether due to increased incidence or
more effective detection, the diagnosis
of young children with autism is
increasing (Fombonne, 2003 a, b). The
number of children with autism spec-
trum disorders is an emerging public
health crisis, with the Centers for
Disease Control and Prevention
reporting that one in 150 children who
are born this year will be affected, an
increase of 172% in diagnosis over the past decade (Centers for Disease Control and Prevention, 2007).
Autism diagnostic criteria
Of the autism spectrum disorders, the most prominent is autism, which is characterized by the presence of restricted or repetitive behaviors in addition to the social and commu- nicative deficits mentioned above. This constellation of behaviors must emerge prior to three years of age for a child to receive a diagnosis of autism (American Psychiatric Association, 2000).
A core deficit of autism is a significant deficit in social reciprocity. These social difficulties manifest themselves behaviorally in a number of ways: poor modulation of non- verbal social behaviors, such as eye-to-eye gaze for the pur- pose of exchanging social affect and intent, lack of social and emotional reciprocity, and an absence of shared enjoyment with others (Lord et al., 1989). This profile of behaviors results in significant problems in the development of peer relationships (American Psychiatric Association, 2000).
From the earliest points in development, typically devel- oping children show a clear interest in those around them. In contrast, deficits in early social responsivity are present in infants and toddlers who go on to receive a diagnosis of autism. For example, failure to orient when one’s name is called is an early “red flag” behavior associated with a later diagnosis (Landa, 2007). This lack of response to such a salient social signal is a powerful example of early deficits in social reciprocity. Accordingly, later in childhood and
“Results from this area of inquiry will move the field forward significantly by providing basic data to guide focused interventions related to speech perception and processing in the population of children with ASD.”
through adulthood, individuals with autism are less likely to seek out and engage in social play with peers than typically developing children (Lord and Magill-Evans, 1995).
Individuals with autism also exhib- it significant delays in the development of communication in both non-verbal and verbal communicative behavior. Deficits in non-verbal communication include a reduced amount of both manual gestures, e.g., in the use of pointing to bring one’s attention to either a proximal or distant object (Baranek, 1999) and in pre-linguistic vocalization, such as babbling and early vocal play (Landa, 2007). Moreover, the
production of spoken language is strongly affected in this population. An estimated 25% of children with autism never develop functional language skills (Klinger et al., 2002). Even those affected children who develop the ability to communi- cate verbally exhibit delays in both language acquisition and use such that they begin to speak later and at a significantly slower rate than their typically developing peers (Lord and Paul, 1997). For those individuals with autism who develop spoken language, the initiation of and ability to maintain conversation is typically severely restricted. Other common features of the language of individuals with autism are stereo- typed or idiosyncratic patterns. For example, the speech of individuals with autism may be high in pitch, uninflected and robot-like or sing-song in nature (Rapin, 2001). Echolalic speech is repetition of the speech of others that sometimes appears to be used communicatively (Loveland and Tunali-Kotoski, 1997). Stereotyped speech refers to high- ly repetitive, highly specific language that is often centered on inappropriately formal and arbitrary topics (Lord et al., 1989). Stereotyped speech can interfere with the child’s over- all quality of social interactions, not only because the topic is unusual and highly specific to an individual, but also because it is typically not well integrated into conversation (Lord et al., 1989).
Finally, individuals with autism display restricted, repet- itive or stereotyped behaviors. These behaviors can be mani- fested in a number of ways, such as intense preoccupations with unusual interests or parts of objects. For example, an affected child may focus exclusively on spinning the wheels
8 Acoustics Today, October 2007