The effects of bilateral electric and bimodal electric--acoustic stimulation on language development

There is no doubt that cochlear implants have improved the spoken language abilities of children with hearing loss, but delays persist. Consequently, it is imperative that new treatment options be explored. This study evaluated one aspect of treatment that might be modified, that having to do with bilateral implants and bimodal stimulation. A total of 58 children with at least one implant were tested at 42 months of age on four language measures spanning a continuum from basic to generative in nature. When children were grouped by the kind of stimulation they had at 42 months (one implant, bilateral implants, or bimodal stimulation), no differences across groups were observed. This was true even when groups were constrained to only children who had at least 12 months to acclimatize to their stimulation configuration. However, when children were grouped according to whether or not they had spent any time with bimodal stimulation (either consistently since their first implant or as an interlude to receiving a second) advantages were found for children who had some bimodal experience, but those advantages were restricted to language abilities that are generative in nature. Thus, previously reported benefits of simultaneous bilateral implantation early in a child's life may not extend to generative language. In fact, children may benefit from a period of bimodal stimulation early in childhood because low-frequency speech signals provide prosody and serve as an aid in learning how to perceptually organize the signal that is received through a cochlear implant.