Related Experiment Videos
Bimodal Cochlear Implant Listeners' Ability to Perceive Minimal Audible Angle Differences.
Ashley Zaleski-King1, Matthew J Goupell2, Dragana Barac-Cikoja1
1Department of Speech and Hearing Sciences, Gallaudet University, Washington, DC.
Journal of the American Academy of Audiology
|November 13, 2018
Summary
Bimodal listeners, using a cochlear implant (CI) and hearing aid (HA), struggle with sound localization. Even with device synchronization, most could not accurately determine sound source locations, indicating significant challenges for spatial awareness.
Area of Science:
- Audiology
- Neuroscience
- Biomedical Engineering
Background:
- Bilateral hearing, combining cochlear implant (CI) and hearing aid (HA), ideally enhances sound localization and speech understanding.
- However, bimodal listeners often experience inconsistent benefits from using both devices.
- Preserving interaural time and level differences (ITDs and ILDs) is crucial for sound source localization in complex environments.
Purpose of the Study:
- To assess bimodal listeners' sensitivity to spatial location changes using a minimum audible angle (MAA) task.
- To investigate if bimodal listeners can utilize binaural cues for sound localization when using a CI and HA simultaneously.
Main Methods:
- Seven adult bimodal CI users with contralateral HA use participated.
- Loudness balancing and inter-device delay (IDD) tasks were performed to assess device synchronization.
- Minimum audible angle (MAA) performance was measured with and without IDD correction.
Main Results:
- Most bimodal listeners struggled with loudness balancing and perceiving interaural time differences.
- Only three out of seven participants consistently achieved above-chance MAA performance, even with IDD correction.
- Listeners' inability to use monaural loudness cues further highlighted difficulties in spatial discrimination.
Conclusions:
- Sound localization is significantly challenging for most bimodal listeners.
- Loudness imbalances and inter-device delays do not appear to be the primary cause of localization difficulties.
- While HA amplification may create overlapping frequency regions, it doesn't guarantee improved spatial discrimination for bimodal users.