Does acoustic fundamental frequency information enhance cochlear implant performance?

Low-frequency information via an acoustic aid has been shown to increase speech intelligibility in noise for cochlear implant (CI) listeners. It has been suggested that fundamental frequency (F0) provides this advantage. This study aimed to investigate the contribution of F0.

Seven cochlear implant users having residual hearing at 125, 250, and 500 Hz contralateral to the implant were recruited. Speech intelligibility in noise was measured using an adaptive procedure for three listening conditions: (1) CI alone, (2) CI plus filtered acoustic information contralaterally, and (3) CI plus acoustic F0 contralaterally. In condition 2, the sentence material was low-passed at 500 Hz and presented via an insert earphone into the contralateral ear. In condition 3, F0 was extracted using Praat and presented as a sine wave with the same F0 variation over time as the original sentence.

Although benefit was observed when low-frequency information was added for the majority of participants, on average no statistically significant difference was found for the three listening conditions.

These results are not consistent with current literature. It is proposed that glimpsing cues may be responsible for the advantage observed in previous studies; in this study, both target and masker were presented in the acoustic condition and this may explain the discrepancy.

The benefit of additional acoustic information may be highly variable and individual to participants, but on average no statistically significant difference was seen.