The Effect of Hearing Aid Bandwidth and Configuration of Hearing Loss on Bimodal Speech Recognition in Cochlear Implant Users

Objectives: (1) To determine the effect of hearing aid (HA) bandwidth on bimodal speech perception in a group of unilateral cochlear implant (CI) patients with diverse degrees and configurations of hearing loss in the nonimplanted ear, (2) to determine whether there are demographic and audiometric characteristics that would help to determine the appropriate HA bandwidth for a bimodal patient. Design: Participants were 33 experienced bimodal device users with postlingual hearing loss. Twenty three of them had better speech perception with the CI than the HA (CI>HA group) and 10 had better speech perception with the HA than the CI (HA>CI group). Word recognition in sentences (AzBio sentences at +10 dB signal to noise ratio presented at 0° azimuth) and in isolation [CNC (consonant-nucleus-consonant) words] was measured in unimodal conditions [CI alone or HAWB, which indicates HA alone in the wideband (WB) condition] and in bimodal conditions (BMWB, BM2k, BM1k, and BM500) as the bandwidth of an actual HA was reduced from WB to 2 kHz, 1 kHz, and 500 Hz. Linear mixed-effect modeling was used to quantify the relationship between speech recognition and listening condition and to assess how audiometric or demographic covariates might influence this relationship in each group. Results: For the CI>HA group, AzBio scores were significantly higher (on average) in all bimodal conditions than in the best unimodal condition (CI alone) and were highest at the BMWB condition. For CNC scores, on the other hand, there was no significant improvement over the CI-alone condition in any of the bimodal conditions. The opposite pattern was observed in the HA>CI group. CNC word scores were significantly higher in the BM2k and BMWB conditions than in the best unimodal condition (HAWB), but none of the bimodal conditions were significantly better than the best unimodal condition for AzBio sentences (and some of the restricted bandwidth conditions were actually worse). Demographic covariates did not interact significantly with bimodal outcomes, but some of the audiometric variables did. For CI>HA participants with a flatter audiometric configuration and better mid-frequency hearing, bimodal AzBio scores were significantly higher than the CI-alone score with the WB setting (BMWB) but not with other bandwidths. In contrast, CI>HA participants with more steeply sloping hearing loss and poorer mid-frequency thresholds (≥82.5 dB) had significantly higher bimodal AzBio scores in all bimodal conditions, and the BMWB did not differ significantly from the restricted bandwidth conditions. HA>CI participants with mild low-frequency hearing loss showed the highest levels of bimodal improvement over the best unimodal condition on CNC words. They were also less affected by HA bandwidth reduction compared with HA>CI participants with poorer low-frequency thresholds. Conclusions: The pattern of bimodal performance as a function of the HA bandwidth was found to be consistent with the degree and configuration of hearing loss for both patients with CI>HA performance and for those with HA>CI performance. Our results support fitting the HA for all bimodal patients with the widest bandwidth consistent with effective audibility. ACKNOWLEDGMENTS: The authors are grateful to Keena Seward and Margaret Miller with assistance on the project. Elad Sagi provided helpful comments on a draft of the manuscript. The authors thank Lisa Potts for providing the CNC-30 test materials. Siemens Hearing Instruments provided the hearing aids used for the study. This research was supported by grant number 1R01DC011329 from the National Institutes of Health/National Institute on Deafness and Other Communication Disorders. This research was also supported by our department, which has a research contract with Cochlear Americas (PI: J. Thomas Roland, Jr). Dr. Svirsky has had research or consulting agreements with Cochlear Americas, Advanced Bionics, and Med-El. Data from some of the participants were included in a previous publication (Neuman & Svirsky 2013). The authors have no conflicts of interest to disclose. Address for correspondence: Mario A. Svirsky, Department of Otolaryngology, New York University School of Medicine, 550 First Avenue (NBV 5E5), New York, NY 10016, USA. E-mail: mario.svirsky@nyumc.org Received August 30, 2017; accepted May 27, 2018. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

from #Audiology via ola Kala on Inoreader https://ift.tt/2v5yMhV
via IFTTT