Novel Approaches to Measure Spatial Release From Masking in Children With Bilateral Cochlear Implants
| Autor: | Z. Ellen Peng, Ruth Y. Litovsky |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Masking (art)
medicine.medical_specialty Speech Intelligibility Intelligibility (communication) Audiology Torso Monaural Cochlear Implantation Article Speech and Hearing Cochlear Implants medicine.anatomical_structure Hearing Otorhinolaryngology Squelch Speech Perception Head shadow medicine Humans Speech reception Child Perceptual Masking Binaural recording Mathematics |
| Zdroj: | Ear Hear |
| ISSN: | 1538-4667 |
| Popis: | OBJECTIVES: To investigate the role of auditory cues for spatial release from masking (SRM) in children with bilateral cochlear implants (BiCIs) and compare their performance with children with normal hearing (NH). To quantify the contribution to speech intelligibility benefits from individual auditory cues: head shadow, binaural redundancy, and interaural differences; as well as from multiple cues: SRM and binaural squelch. To assess SRM using a novel approach of adaptive target-masker angular separation, which provides a more functionally relevant assessment in realistic complex auditory environments. DESIGN: Children fitted with BiCIs (N=11) and with NH (N=18) were tested in virtual acoustic space (VAS) that was simulated using head-related transfer functions (HRTFs) measured from individual children with BiCIs behind the ear and from a standard head and torso simulator for all NH children. In Experiment I, by comparing speech reception thresholds (SRT) across four test conditions that varied in target-masker spatial separation (co-located vs. separated at 180-degree) and listening conditions (monaural vs. binaural/bilateral listening), intelligibility benefits were derived for individual auditory cues for SRM. In Experiment II, SRM was quantified using a novel measure to find the minimum angular separation (MAS) between the target and masker to achieve a fixed 20% intelligibility improvement. Target speech was fixed at either +90 or −90-degree azimuth on the side closer to the better ear (+90-degree for all NH children) and masker locations were adaptively varied. RESULTS: In Experiment I, children with BiCIs as a group had smaller intelligibility benefits from head shadow than NH children. No group difference was observed in benefits from binaural redundancy or interaural difference cues. In both groups of children, individuals who gained a larger benefit from interaural differences relied less on monaural head shadow, and vice versa. In Experiment II, all children with BiCIs demonstrated measurable MAS thresholds < 180-degree and on average larger than that from NH children. Eight of 11 children with BiCIs and all NH children had a MAS threshold < 90-degree, requiring interaural differences only to gain the target intelligibility benefit; whereas the other three children with BiCIs had a MAS between 120 and 137-degree, requiring monaural head shadow for SRM. CONCLUSIONS: When target and maskers were separated at 180-degree on opposing hemifields, children with BiCIs demonstrated greater intelligibility benefits from head shadow and interaural differences than previous literature showed with a smaller separation. Children with BiCIs demonstrated individual differences in using auditory cues for SRM. From the MAS thresholds, more than half of the children with BiCIs demonstrated robust access to interaural differences without needing additional monaural head shadow for SRM. Both experiments led to the conclusion that individualized fitting strategies in the bilateral devices may be warranted to maximize spatial hearing for children with BiCIs in complex auditory environments. |
| Databáze: | OpenAIRE |
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