United Kingdom national paediatric bilateral project: Demographics and results of localization and speech perception testing

Abstract

These data represent the diverse population of children with bilateral cochlear implants in the UK from 2010 to 2012. Predictions of outcomes for individual patients are not possible from these data. However, there are no indications to preclude children with long inter-implant interval having the chance of a second cochlear implant.

Limiting asymmetric hearing improves benefits of bilateral hearing in children using cochlear implants

“…6) 1 whereas children who had asymmetric speech perception detected speech 1.2–2.5 dB better when noise moved towards the poorer/second ear than the better/first ear (Figs 6 and 7). This asymmetric use of spatial separation in bimodal and sequential groups falls within the lower range of previously reported 1.8–4 dB asymmetries favouring a better signal to the first implanted ear 33,36,37,45 . The degree of asymmetry measured may have implications for everyday function.…”

“…Measures of speech detection allowed testing of children with wide ranges of age, native language, and developmental ability but detection is an easier task than speech recognition. This explains the lower SNR levels in this study compared to the −9 to +7 dB SNR speech recognition thresholds reported for children with normal hearing 55,56 or CIs 39,44,45,57 . The ability to detect and understand speech in noisy conditions improves with age 33,55,56 as the auditory system matures.…”

“…All groups showed ~3–4 dB spatial unmasking which was poorer than the normal range of 5–10 dB 1,35,37,55,56 , but within the 2–4 dB range reported for sequential bilateral CI and bimodal users 33,35–37,44,45 . More importantly, simultaneous groups took similar advantage of spatial unmasking when noise moved to either side (Fig.…”

“…Poorer (reduced) SNR on one side signals a potential for reduced speech perception in the condition when the “preferred” or better ear is masked by noise. Although asymmetries in spatial hearing can decrease after 3 years of bilateral input as the second ear’s performance improves 45 , the present cohort used their bilateral devices for 3–6 years, suggesting that these aural asymmetries are long-lasting.…”

“…These studies revealed better speech thresholds in noise while using two implants, but asymmetric preference for a better signal at the first implanted ear in several children who underwent sequential implantation. Studies with larger cohorts of children (≥50) suggest that children benefit from bilateral implants despite delays to bilateral input but longer delays impair performance in the second hearing ear, creating asymmetric abilities between the two ears for understanding speech 1,40–43 and for spatial hearing 44,45 . One of the main problems of relating existing speech perception data to electrophysiological findings is that only a few of the behavioural studies include children with very short or no delays to bilateral implantation 1,45 , leaving a question about the most appropriate timing of bilateral input to prevent behavioural consequences of aural preference.…”