Recovery of speech perception performance after prolonged auditory deprivation: case study.

The case reported here, a 26-year-old woman, has a bilaterally symmetric, severe-to-profound, sensorineural hearing loss, acquired early in life. Phoneme recognition scores were essentially symmetric at the onset of the investigation. She was basically monaurally aided from age 4 to age 24, at which time a loss of function in the aided ear prompted the change to binaural amplification. When monaurally aided, this subject had consistently given phoneme recognition scores around 80 percent and 40 percent in the aided and unaided ears, respectively, even though the pure-tone thresholds were almost identical. After several months of hearing aid use, phoneme recognition in the previously unaided ear rose to 75 percent. At the time of writing, this subject is able to hold unstructured telephone conversations via this ear. These data suggest that the earlier poor performance of the unaided ear was due, not to an irreversible loss of peripheral function, but to a lack of experience in interpreting the patterns of neural stimulation generated by that ear.