Effects of age and hearing mechanism on spectral resolution in normal hearing and cochlear-implanted listeners

Abstract

Spectral resolution limits speech perception with a cochlear implant (CI) in post-lingually deaf adults. However, the development of spectral resolution in pre-lingually deaf implanted children is not well understood. Acoustic spectral resolution was measured as a function of age (school-age versus adult) in CI and normal-hearing (NH) participants using spectral ripple discrimination (SRD). A 3-alternative forced-choice task was used to obtain SRD thresholds at five ripple depths. Effects of age and hearing method on SRD and spectral modulation transfer function (SMTF) slope (reflecting frequency resolution) and x-intercept (reflecting across-channel intensity resolution) were examined. Correlations between SRD, SMTF parameters, age, and speech perception in noise were studied. Better SRD in NH than CI participants was observed at all depths. SRD thresholds and SMTF slope correlated with speech perception in CI users. When adjusted for floor performance, x-intercept did not correlate with SMTF slope or speech perception. Age and x-intercept correlations were positive and significant in NH but not CI children suggesting that across-channel intensity resolution matures during school-age in NH children. No evidence for maturation of spectral resolution beyond early school-age in pre-lingually deaf implanted CI users was found in the present study.

Age-Related Performance on Vowel Identification and the Spectral-temporally Modulated Ripple Test in Children With Normal Hearing and With Cochlear Implants

“…While these findings, as well as those from previous studies in NH children, indicate that pediatric CI users’ performance on psychoacoustic tasks should improve with age (but perhaps on a delayed time course), previous studies have found no relationship between chronological age and SRD performance ( Horn et al., 2017 ; Jung et al., 2012 ) or speech identification scores ( Eisenberg et al., 2002 ) in early-implanted, school-age children with CIs. Evidence from structural examinations of auditory system development with auditory deprivation (e.g., J. K. Moore & Linthicum, 2007 ) suggests that aided hearing age or amount of time with the CI may instead be better predictors of auditory capabilities in these children.…”

“…A potential issue with the conventional spectral ripple tasks used in many previous studies is that subjects may rely on local loudness cues to discriminate between stimuli ( Aronoff & Landsberger, 2013 ). Intensity resolution continues to mature through adolescence in NH children ( Horn et al., 2017 ; Maxon & Hochberg, 1982 ) and in children with CIs ( Park et al., 2015 ) and therefore cues in the intensity domain may confound results on this test. The SMRT, which uses spectral ripples with drifting modulation phases to diminish potential within-channel loudness cues, may be more appropriate than traditional SRD tasks for use with pediatric populations.…”

“… Eisenberg, Shannon, Martinez, Wygonski, & Boothroyd, 2000 ), and the timeline of auditory cortical development corresponds well with these improvements in NH children’s speech perception abilities (e.g., Eggermont & Ponton, 2003 ). Despite copious evidence of the relationship between development and auditory task performance in NH children, chronological age has not been found to predict pediatric CI users’ speech recognition scores (e.g., Eisenberg, Martinez, Holowecky, & Pogorelsky, 2002 ) or performance on other psychoacoustic tests (e.g., Horn et al., 2017 ; Jung et al., 2012 ; Landsberger, Padilla, Martinez, & Eisenberg, 2017 ). These null findings may have resulted from the tremendous variability in outcomes of children with CIs.…”

“…This is a particularly significant problem for children with CIs because a child’s ability to perceive speech sounds is critical for development of verbal speech and language skills (e.g., Eisenberg et al., 2016 ; Niparko et al., 2010 ). Early-implanted children who receive a CI prior to 5 years of age often exhibit the most favorable outcomes in verbal speech and language development; nevertheless, speech perception performance remains highly variable even among these children ( Horn et al., 2017 ; Jung et al., 2012 ; Tyler et al., 1997 ; N.-Y. Wang et al., 2008 ).…”

Flaws in Spectral Ripple Stimuli for Listeners with Cochlear Implants

“…In light of the numerous spectral cues involved in differentiating speech sounds that CI listeners are known to misperceive (Munson et al 2003), it seems reasonable to suspect that 71 spectral resolution is a chief limiting factor of the device. To better understand the 72 mechanisms that determine cochlear implant efficacy, translational research has 73 become increasingly concerned with the quantification of spectral resolution in CI 74 listeners (Won et al 2007;Won et al 2011a;Drennan et al 2010;Drennan et al 2014; 75 Shim et al 2014;Drennan et al 2015;Horn et al 2017).…”