Facilitating language processing for children with hearing loss

Many children with hearing loss can achieve functional language comprehension via the use of hearing aids and/or cochlear implants. However, even if these children can understand spoken language successfully, they may still struggle with some aspects of processing the speech signal. For example, adolescent cochlear implant users have been shown to process language more slowly than their peers with normal hearing, and children who use hearing aids may expend greater effort to process language than their normal­ hearing peers. Slow and effortful processing are associated with a range of poor outcomes, such as difficulties with social interaction, lower academic achievement, and increased incidence of stress and fatigue. This thesis therefore examined ways in which spoken language processing may be made faster and less effortful for children with hearing loss. We considered that both bottom-up and top-down information may be exploited for this purpose: The bottom-up information available to the listener may be enriched via the presentation of visual speech cues ( e.g., the speaker's facial movements) and top-down information may be enriched via informative semantic context, for example. Children with hearing loss may be able to use these cues to improve their processing speed and/or effort. Alternatively, they may be unable to make use of one or both of these sources of information due to the effects of auditory deprivation or degradation during language development. We also expected to observe considerable variability in the extent to which children with hearing loss benefited from these different types of information. Therefore, a secondary aim of the thesis was to attribute some of this variability to individual participant characteristics. The first two studies of the thesis addressed the influence of visual speech cues on processing speed and effort among children with normal hearing ( study one) and children The first two studies of the thesis addressed the influence of visual speech cues on processing speed and effort among children with normal hearing ( study one) and children with hearing loss (study two). We found that the addition of visual speech cues improved processing speed for both groups of children, but reduced effort only for children with normal hearing. The third study compared the use of semantically informative sentence contexts between children with hearing loss and their normal-hearing peers. Children with hearing loss were able to utilise contextual information to process sentences more rapidly and did not perform significantly differently to children with normal hearing. These results indicate that enrichment of both bottom-up and top-down information can facilitate language processing for children with hearing loss, particularly with respect to processing speed. This may lead to practical steps for facilitating effective communication for children with hearing loss and may inform future clinical and/or educational interventions. Furthermore, the findings of this thesis will contribute to our understanding of the use of bottom-up vs. top-down linguistic information in situations where listening is challenging.