Hearing Asymmetry Biases Spatial Hearing in Bimodal Cochlear-Implant Users Despite Bilateral Low-Frequency Hearing Preservation.
Snandan Sharma, Lucas H M Mens, Ad F M Snik and 2 others
PMID 36605011WHAT IT FOUND
Bimodal cochlear implant users localized sounds poorly, with errors averaging 62 degrees.
High-frequency sounds were pulled toward the implanted ear, and low-frequency sounds toward the hearing-aid ear.
Key findings
01Overall sound localization errors were large, averaging 62 degrees across listening conditions and sounds.
02Hearing asymmetry predicted localization bias, but listeners also showed a hearing-aid preference of 18.8 dB not explained by asymmetry alone.
03With the hearing aid on, low-frequency sounds were biased toward the hearing-aid ear, while high-frequency sounds were localized toward the implanted ear.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Only seven participants were tested, and some did not complete all listening conditions, so individual variability was large. The participants had less residual low-frequency hearing than in some earlier studies, which may reduce the benefit of the implant plus hearing aid. The task used short noise bursts in a lab, not speech or everyday sounds, so the findings may not match real-world localization. Participants could not localize elevation, and the study did not test whether long-term use or training reduces the bias. One participant's data had been published separately as a case study.
Declared interests
The supplied publication types list non-U.S. government research support. The text does not state a commercial conflict of interest.
The easy way to misread this
Do not assume that preserved low-frequency hearing in both ears ensures accurate localization. In this study, localization errors were large, and responses were biased toward the hearing-aid ear for low-frequency sounds and toward the implanted ear for high-frequency sounds.