Are Band Importance Functions Related to Conventional Speech Perception Outcomes in Adult Cochlear Implant Listeners?

The purpose of this study was to determine if the pattern of an adult cochlear implant (CI) participant's band importance function (BIF) was associated with speech perception performance using standard assessments (i.e., consonant-nucleus-consonant [CNC] words, Arizona Biomedical [AzBio] sentences).

A total of seven adults (nine ears) with CIs participated, along with nine adults with normal hearing (NH) as a control group. Each participant completed speech recognition measures (CNC word recognition and AzBio sentence recognition) in addition to BIF testing for six 1-octave-wide bands centered on frequencies between 256 and 8487 Hz using filtered monosyllabic words.

The BIFs of NH and CI participants showed highest importance for mid-frequency bands. The BIFs for NH participants were uniform across participants with peak importance for the band with a center frequency around 2 kHz. BIFs for CI participants were variable, although, on average, they placed greater weight on the 2-kHz band. Additionally, the band with a center frequency of around 8 kHz carried the least importance for both groups. Higher speech perception outcomes were not obviously associated with a specific pattern of BIF among CI participants.

Results of this study suggest that adults with CIs have more variable BIFs compared to adults with NH and that higher speech recognition outcomes are not associated with specific patterns of BIFs.