Spatial Release From Masking in 2-Year-Olds With Normal Hearing and With Bilateral Cochlear Implants

Area of Science:

• Audiology
• Developmental Neuroscience
• Speech Perception

Background:

• Spatial release from masking (SRM) is crucial for understanding speech in noisy environments.
• Early auditory development in children with bilateral cochlear implants (BiCIs) is critical for auditory skill acquisition.
• Understanding SRM development in very young children with BiCIs can inform auditory rehabilitation strategies.

Purpose of the Study:

• To evaluate spatial release from masking (SRM) in 2- to 3-year-old children with BiCIs compared to age-matched normal-hearing (NH) toddlers.
• To investigate if early bilateral hearing activation promotes SRM comparable to NH children.
• To assess the potential clinical utility of an SRM paradigm for evaluating bilateral hearing outcomes in young children.

Main Methods:

• Participants included 13 NH toddlers and 13 toddlers with BiCIs (ages 27-36 months).
• Speech reception thresholds (SRTs) were measured for target speech presented in front (0°) with competing sounds either colocated (0°) or spatially separated (+90°).
• SRM was calculated as the difference in SRTs between the front and asymmetrical conditions.

Main Results:

• Speech reception thresholds (SRTs) were higher for the BiCI group compared to the NH group across all conditions.
• Both groups exhibited elevated SRTs in the presence of competing sounds (colocated and separated) compared to quiet conditions, indicating masking.
• Significant SRM was observed only in the NH group. In the BiCI group, the group effect for SRM was not statistically significant, though individual results largely fell within the NH range.

Conclusions:

• The ability to utilize spatial cues for sound source segregation begins to develop by 2-3 years of age in normal-hearing children.
• This spatial hearing ability appears attainable in most young children with bilateral cochlear implants.
• The evaluated paradigm shows promise for clinical assessment of bilateral hearing outcomes in pre-school-aged children.