Fully objective hearing threshold estimation in cochlear implant users using phase-locking value growth functions

Darren Mao, Hamish Innes-Brown, Matthew A. Petoe, Yan T. Wong, Colette M. McKay

Research output: Contribution to journalArticleResearchpeer-review

1 Citation (Scopus)


Cochlear implant users require fitting of electrical threshold and comfort levels for optimal access to sound. In this study, we used single-channel cortical auditory evoked responses (CAEPs) obtained from 20 participants using a Nucleus device. A fully objective method to estimate threshold levels was developed, using growth function fitting and the peak phase-locking value feature. Results demonstrated that growth function fitting is a viable method for estimating threshold levels in cochlear implant users, with a strong correlation (r = 0.979, p < 0.001) with behavioral thresholds. Additionally, we compared the threshold estimates using CAEPs acquired from a standard montage (Cz to mastoid) against using a montage of recording channels near the cochlear implant, simulating recording from the device itself. The correlation between estimated and behavioural thresholds remained strong (r = 0.966, p < 0.001), however the recording time needed to be increased to produce a similar estimate accuracy. Finally, a method for estimating comfort levels was investigated, and showed that the comfort level estimates were mildly correlated with behavioral comfort levels (r = 0.50, p = 0.024).

Original languageEnglish
Pages (from-to)24-33
Number of pages10
JournalHearing Research
Publication statusPublished - 1 Jun 2019


  • Cochlear implant
  • Cortical response
  • EEG
  • Electrical dynamic range
  • Objective threshold estimation
  • Phase-locking value

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