Effects of Frequency-Composition Algorithm and Phoneme-Based Auditory Training in Older Hearing Aid Users

Frequency-lowering (FL) algorithms improve the audibility of high-frequency sounds by shifting inaudible high-frequency components to audible low-frequency regions. However, the FL algorithm has yielded mixed findings. This study involved two experiments. The first experiment investigated whether objective and subjective auditory outcomes would be enhanced by activating frequency composition (Fcomp), which is a type of FL technique. The second experiment determined whether auditory training with Fcomp activation would provide perceptual benefits to older hearing aid users.

Twelve older hearing aid users with moderate to profound high-frequency sensorineural hearing loss participated in this study. In Experiment I, all participants received a 4-week adaptation period to Fcomp before the measurement, and then the influence of Fcomp was evaluated. In Experiment II, among the 12 participants in Experiment I, five received 8-week phoneme-based auditory training while activating Fcomp, whereas the remaining seven did not receive training but continued to use Fcomp as non-trained controls.

In Experiment I, 4-week passive accli-matization period to Fcomp did not improve speech-in-quiet recognition or self-perceived sound quality. In Experiment II, active pho-neme-based training enhanced recognition of consonants and words as well as better speech-quality ratings for trained participants. The consecutive use of Fcomp did not lead to any differences for non-trained participants.

Overall, phoneme-based auditory training would allow older hearing aid users to relearn frequency-lowered speech sounds and reduce phonetic confusion. However, the analytical training approach did not lead to transfer to sentence recognition or overall satisfaction with the hearing aids.