Cochlear implants (CIs) provide deaf individuals with access to auditory information by converting sound into an electrical signal that is delivered to the auditory nerve. Although CIs promote spoken language in prelingually deafened children, with greater success typically associated with earlier implantation, there is large variability in speech and language outcomes. In addition, the process by which these young CI users acquire language is poorly understood. Thus, there is a need to identify auditory and prelingual skills that subserve language acquisition in these children so that aural habilitation can be modified to maximize performance. Although static measures are commonly used to document speech and language outcomes in children who use CIs, those measures are unable to capture the dynamic aspects of spoken language acquisition at ages when language is emerging. The long term goal of the proposed research is to employ well-established behavioral methodologies traditionally used with typically-developing infants who have normal acoustic hearing to identify auditory and spoken language skills in children under the age of 3 years who use CIs. The benefits of using these behavioral methodologies are the ability to quantify how young children actively process both nonverbal auditory and linguistic content as well as highlight individual differences. Speech is fluid and without pauses. Thus, a requisite skill for processing the speech signal is the ability to temporally process rapidly changing sequential auditory information. If children have difficulty resolving temporal auditory cues, they may miss the linguistic message or lose an opportunity to learn a new word. When this occurs, children may rely on other contextual information, like redundant visual cues within the speech signal (i.e., lipreading), to resolve the linguistic content.
Aim 1 of the proposed research will assess the ability of 2-year-old CI users, and their peers with normal acoustic hearing matched on chronological age or hearing experience, to resolve temporal cues within nonverbal auditory stimuli during an auditory visual habituation/recognition memory task.
Aim 2 will assess whether young CI users and their normal hearing peers can benefit from multimodal (auditory + visual) information during a spoken word recognition task. Children will participate in a """"""""looking-while-listening"""""""" task that will measure how quickly and how accurately they can recognize a known object after hearing, or hearing and seeing, its spoken label. Finally, statistical analyses will be used to determine if children who are better able to temporally process nonverbal auditory stimuli are better performers on the spoken word recognition task or if visual cues are necessary to improve language processing.
In light of the variable outcomes that are currently achieved by deaf children who use cochlear implants, it would be beneficial if families and professionals working with these children knew what factors contribute to long-term success. The current application addresses this issue. Understanding how young children with cochlear implants acquire and process spoken language is a public health issue since this knowledge can shape intervention and educational efforts.