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Updated: Jul 6, 2026

Electrically Evoked Stapedius Reflex Measurements in Cochlear Implantation and Its Application in the Postoperative Fitting Process
Published on: June 21, 2024
Sensitivity to interaural level difference and loudness growth with bilateral bimodal stimulation
Tom Francart1, Jan Brokx, Jan Wouters
1Exp ORL, Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium. tom.francart@med.kuleuven.be
This study measured interaural level difference (ILD) sensitivity in cochlear implant (CI) and hearing aid (HA) users. The average just noticeable difference (JND) for pitch-matched sounds was 1.7 dB, indicating good sound localization ability.
Area of Science:
- Audiology
- Neuroscience
- Bioacoustics
Background:
- Interaural level difference (ILD) is crucial for sound source localization.
- Binaural hearing with a cochlear implant (CI) and a hearing aid (HA) presents unique challenges for auditory perception.
Purpose of the Study:
- To investigate the sensitivity to ILD in individuals with a unilateral CI and a contralateral HA.
- To measure the just noticeable difference (JND) in ILD and loudness growth functions for simultaneous electric and acoustic stimulation.
Main Methods:
- 10 participants with a unilateral CI and contralateral HA were recruited.
- Just noticeable difference (JND) in ILD and loudness growth functions were measured using simultaneous pulse train (CI) and sinusoid (HA) stimulation.
- Stimuli were pitch-matched for electric and acoustic signals.
Main Results:
- The mean JND for pitch-matched electric and acoustic stimulation was 1.7 dB.
- Loudness growth functions exhibited a linear relationship on a decibel-versus-microampere scale.
- The slope of the loudness growth function was found to be dependent on individual dynamic ranges.
Conclusions:
- Individuals with a unilateral CI and HA demonstrate measurable sensitivity to ILD.
- Pitch-matched electric and acoustic stimulation allows for the assessment of binaural hearing cues in hybrid hearing scenarios.
- Dynamic range significantly influences loudness perception in this user group, impacting ILD processing.
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