| Studies have found that many new hearing aid users experience a gradual improvement in speech performance over time with performance typically peaking 6-12 weeks following hearing aid fitting. The delayed improvement may be due to neural reorganization of the auditory system following the re-introduction of auditory input through amplification. Animal and human studies have shown that a high-frequency hearing loss can cause expansion of intact adjacent frequency regions in cortex. The expanded regions take over the deprived cortical areas. Individuals with hearing impairment have been shown to have difficulty with frequency discrimination in deprived frequency regions. Auditory training (i.e., frequency discrimination training) has been shown to result in the expansion of cortical representations of the trained frequencies, and result in perceptual and neurophysiological changes in less than 10 days. The hypothesis is that, following amplification, frequency-sweep discrimination training in the previously deprived frequency regions can facilitate improvements in speech performance following the introduction of amplification. Twelve newly-amplified listeners hearing impairment participated in this study. Prior to training, all listeners performed frequency-sweep discrimination testing at 500, 1000, 2000, and 4000 Hz, consonant identification and sentence identification testing in quiet and noise, and an initial APHAB. The group will received half an hour of training per day for 10 days on frequency-sweep discrimination 2000 Hz. Following 10 days of training, the group again performed the pre-training testing and completed a questionnaire of subjective hearing aid benefit. Although intensive auditory training did not lead to significant improvements in consonant identification or place of articulation, there were significant improvements in sentence identification and perceived hearing aid benefit. High-frequency discrimination training appears to generalize to other frequencies and have a global effect on speech understanding. |
