Relationship Between Psychophysical Tuning Curves and Vowel Identification in Noise in Children and Adults With Cochlear Implants.

Purpose: Perceptual outcomes in cochlear implant (CI) listeners are influenced by the quality of the interface between individual CI electrodes and their target auditory neurons (i.e., electrode-neuron interface [ENI]). Poor ENI increases the likelihood of CI channel interaction, which may lead to the smearing of sound frequency information, reduced spectral resolution, and, thus, errors in identifying speech sounds, particularly when there is background noise. This research note aims to present preliminary data on whether psychophysical tuning curves (PTCs), as a measure of channel interaction and an indirect measure of ENI, relate to vowel identification in noise in children and adults with CIs.

Method: PTCs and medial vowel identification in four-talker babble noise were obtained for eight children (12 ears) and eight adults (eight ears) with CIs. PTCs were measured for one electrode in the middle of the array using direct stimulation and a standard two-interval, two-alternative forced choice procedure.

Results: Adults and children with sharper PTCs performed better on vowel identification in noise (F = 6.63, p = .02), demonstrating an association between less channel interaction and better vowel identification in noise in CI listeners irrespective of age. Although no statistically significant difference was found between children and adults in their PTC sharpness, children performed better than adults on vowel identification in noise (F = 5.38, p = .034).

Conclusions: The findings provide evidence that the sharpness of the PTC on a mid-array electrode is related to vowel identification in noise for CI listeners. Vowel identification in noise and PTC sharpness could be further investigated for use in developing personalized programming strategies that enhance the transmission of spectral cues crucial for recognizing vowel sounds.