Phantom Stimulation for Cochlear Implant Users With Residual Low-Frequency Hearing.

Area of Science:

• Audiology
• Biomedical Engineering
• Neuroscience

Background:

• Cochlear implants (CIs) aim to restore hearing by electrically stimulating the auditory nerve.
• Phantom stimulation is a technique to extend the pitch range of CIs towards the apical cochlea.
• Residual low-frequency hearing in CI users can be leveraged for improved speech perception.

Purpose of the Study:

• To evaluate phantom stimulation for conveying low-frequency information in CI users with residual hearing.
• To compare speech reception thresholds between electric-acoustic stimulation (EAS) and electric stimulation with phantom stimulation (EPS).
• To investigate the impact of spectrally overlapped speech information on speech reception when using simultaneous acoustic and phantom stimulation.

Main Methods:

• A repeated-measures design was used with 14 CI users having ipsilateral residual hearing.
• Phantom stimulation was implemented with varying compensation coefficients (σ) to shape electric fields.
• Speech reception thresholds were measured for electric stimulation alone, EAS, EPS, and simultaneous acoustic and phantom stimulation (EAS+PS).

Main Results:

• Both EAS and EPS significantly improved speech perception compared to electric stimulation alone.
• No significant difference in speech reception thresholds was found between EAS and EPS.
• Speech perception deteriorated when acoustic and phantom stimulation conveyed spectrally overlapped information, with deterioration increasing with greater overlap.

Conclusions:

• CI users with low-frequency residual hearing benefit from acoustic information via EAS.
• Phantom stimulation can improve speech reception thresholds in EAS users when acoustic stimulation is absent.
• Combining acoustic and phantom stimulation with spectral overlap negatively impacts speech perception compared to EAS.