Acquisition of Speech in Children
As many as 12,000 children with significant hearing impairment are born in the U.S. every year (Dept. of Health and Human Services, 2004). For these children, many with sensorineural hearing loss (SNHL), the successful acquisition of age-appropriate speech intelligibility is a critical outcome to their overall communication effectiveness. Speech acquisition in children whose profound hearing impairment is identified at older chronological ages has been extensively studied (e.g., Miyamoto, Kirk, Svirsky, & Sehgal, 1999; Serry & Blamey, 1999; Tye-Murray, Spencer, & Gilbert-Bedia, 1995). However, among children identified at birth with varying levels of auditory sensitivity, or who have various auditory histories and auditory experience with cochlear implants (CIs) and/or hearing aids (HAs), less is understood about how to utilize the clinical significance of two key components that underlie the acquisition of the process of acquiring speech intelligibility; speech production and auditory perception.
In the proposed longitudinal study, data will be gathered from children identified at birth with mild, moderate, and severe unaided levels of SNHL compared with data from chronologically age-matched children with normal hearing (NH). Data from two domains, speech production and auditory perception, will be collected s. Auditory perception outcomes will be measured using, the Auditory Steady-State Response technique (ASSR). ASSR enables analysis of potential relationships between speech production and auditory perception in young children who may not be willing or able to consistently participate in behavioral responses to auditory tasks during the developmental period in which changes in their spontaneous speech are easily monitored. The ASSR allows researchers to study these children, who comprise a unique population from a research perspective, given that their SNHL is discovered at birth. The children are form also a new population relative to advances in instrumentation technology. Longitudinal data collection on speech production and auditory perception analyzing the relationships among these domains can support development more valid and comprehensive assessment and intervention protocols for this chonologically and developmentally younger population by considering critical inputs to speech intelligibility.
This study also provides an opportunity to test a model of the relationship among speech production and auditory perception, labeled the Association Hypothesis (AH). In this hypothesis, these two domains and their sub-domains are considered to be emerging interactive capacities within a complex system. The biological capacity to produce speech interacts with the capacity to auditorily perceive spoken input with the hearing system relative to neural coding of auditory input; this latter capacity will be probed with the ASSR. Because contemporary research paradigms have treated these domains as separate, each with its own evolutionary and developmental trajectory, little is known about how they may be related, and if so, the nature of the relationship(s). The Association Hypothesis will be tested by assessing the interaction of the two domains through correlating participant scores on dependent variables within each domain.
Specific aims are as follows: Track speech output patterns that provide ongoing behavioral evidence of the status of the production system underlying emergence of speech intelligibility, Track auditory neural encoding of spectral and temporal aspects of sound linked with basic acoustic products of speech input and output patterns providing an auditory substrate for acquiring intelligible speech.
This submission is informed by a 2006 NIDCD workshop, “Outcomes Research in Children with Hearing Loss."
Barbara Davis, Professor, Department of Communication Sciences and Disorders The University of Texas at Austin Craig Champlin, Professor, Department of Communication Sciences and Disorders,, The University of Texas at Austin Emily E. Tobey, Professor, Division of Behavioral and Brain Sciences The University of Texas at Dallas