ERPs and Syntactic Processing: Investigating hearing Aid Efficacy in Restoring Auditory Access to Hard-of-Hearing Adults
Given our understanding of how hearing aids (HAs) function and the benefits they provide by spectrally tailoring acoustic stimuli to the individual user, two assumptions can be made. First, that hard-of-hearing (HH) individuals with a history of HA use should have sufficient auditory access to the speech signal when properly fit and using their HAs, and second that those same individuals should have the ability to detect syntactic incongruities when aided. The first purpose of this study was to support the assumption that HAs sufficiently restore enough spectral detail to allow for the comprehension of speech and the identification of syntactic errors within that speech. The second was to provide evidence that analysis of the P600, a late-occurring event-related potential, the presence of which is indicative of syntactic cognitive processing, could be used as the objective tool to assess the efficacy and benefit of HAs. It was hypothesized that HH individuals would have P600 responses only with the use of their HAs and that the brain would not be able to correct or supplement missing information in the absence of the appropriate acoustic signals. Results showed that the P600 was only present in the aided condition and in response to sentences with incorrect syntax structures. This not only supported the assumption that HAs provide sufficient spectral detail, but also the hypothesis that the brain would not be able to supplement missing syntactic information, even in peri- and postlingually deafened adults. Though only based on data gathered from a very small sample size (N=6), the study was able to accomplish both objectives. However, further research is needed to determine if there is a more practical clinical utility for the analysis of the P600.