Applying adult hearing aid concepts to children: A feasibility study

The results of this study suggest that the recommended fitting protocol for the Adapto hearing instrument (i.e., using an open earmold) is problematic in young children due to the size of the ear canal. Not only was it difficult to achieve an open fitting, it was difficult to reach target gain due to acoustic feedback. As a result of these problems, all four subjects were fitted with fully occluding earmolds. Fortunately, under these conditions, the ability of the devices to meet target gain (and to a lesser extent maximum output) values across frequencies was superior to that of the subjects' previous devices. This type of flexibility is important in fitting young children since they tend to have a higher incidence of unusual hearing loss configurations than adults. In addition, compared with their own hearing aids, greater high-frequency gain and improvements in the perception of some high-frequency consonants were observed in all four children when they wore the test instruments. Such improvements may have important consequences for speech and language development, since recent results suggest that the limited bandwidth of hearing aids can have a negative influence on the acquisition of fricatives in infants and young children. When all of the subjective and objective data from both parents and children were combined, a dear improvement with the test fitting over the previous hearing instruments was seen in only one subject (S1). In the other cases, the parent/child or subjective/objective results were ambiguous or in conflict. This lack of agreement may be explained, in part, by the poor correlation between the responses of the parents and children on the questionnaires. However, the underlying reasons for this disagreement are not well understood and warrant further study. We also concluded that, although the questionnaires were designed for children, some of the questions might not be meaningful to children with prelingual hearing loss. Such children may be unable to answer questions about sound quality or the naturalness of their own voices. They also have difficulty comparing their experiences with those of people with normal hearing. Finally, follow-up questions and discussions with the children after they completed the questionnaires revealed that their answers and decisions were often based upon factors that had little to do with hearing aid performance (e.g., hearing aid color, on/off switch). As new technologies become available and studies are designed to evaluate how well they can be applied to infants and young children with hearing loss, it will be important to consider these potential complications. Recently, all four families were contacted for an update on their hearing aid experiences since the completion of this study approximately 6 months earlier. Despite the preferences indicated at the end of the study, all four children have been wearing the Adapto hearing aids full time.