Listening effort in children with severe-profound sensorineural unilateral hearing loss

Abstract

Title: Listening effort in children with severe-profound sensorineural unilateral hearing loss. Name: Ilze Oosthuizen Supervisor: Prof. De Wet Swanepoel Co-supervisors: Prof. Lidia Pottas & Prof. Erin M. Picou Department: Speech-language Pathology and Audiology Degree: D. Phil Communication Pathology (Audiology)

Unilateral hearing loss, affecting up to 3% of school-aged children, is known to put this population at risk for speech-language, academic, and behavioral difficulties. These risks can even be more pronounced for children with severe-profound sensorineural unilateral hearing loss (described hereafter as limited useable hearing unilaterally, LUHU) relative to peers with normal hearing. Children in school spend the greater part of their school day listening, often in acoustical challenging situations. This can result in increased listening effort that can negatively affect academic performance and quality of life. Therefore, this research project focused on determining listening effort in school-aged children with limited useable hearing unilaterally, as well as evaluating the effect of non-surgical intervention options on the listening effort experienced by these children. Specific outcomes of digit triplet recognition and response times were focused on throughout the research project.

Study I aimed to develop novel, low-linguistic listening effort paradigms (single- and dual-task), with digit triplets as speech stimulus, that can be used in school-aged children form multilingual backgrounds (English as native language vs English as non-native language). A total of 60 school-aged children, aged 7 to 12 years, with normal hearing participated in the first study, 30 per language group. Significant effects of noise on response times were evident during both single-task (p < .001, ηp2 = 0.58) and dual-task paradigms (p < .001, ηp2 = 0.23), with an increase in noise resulting in longer response times, reflecting increased listening effort. The data also revealed a maturation effect for digit triplet recognition during both tasks with older children presenting with improved performance of speech recognition in noise. A significant relationship between age and dual-task visual response times (r = -0.39, p < .0001) was evident, with response times decreasing with an increase in age. Language background had no significant effect on digit triplet recognition performance or response times (p > .05), demonstrating practical utility of these low-linguistic paradigms for measuring listening effort in school-aged children from multilingual backgrounds.

Consequently, Study II aimed to determine if school-aged children with LUHU experience more listening effort relative to peers with normal hearing by employing the low-linguistic single-task paradigm as well as subjective ratings. Specifically, two groups of school-aged children (aged 7-12 years) participated, 19 children with LUHU and 18 children with normal hearing bilaterally. Participants completed digit triplet recognition tasks in quiet and in noise (-12 dB signal-to-noise ratio) in three loudspeaker conditions: midline, direct, and indirect. Verbal response times during the recognition task were interpreted as behavioral listening effort. Subjective ratings of “task difficulty” and “hard to think” were interpreted as subjective listening effort. Participant age was included as a covariate in analysis of behavioral data. Results indicated that noise significantly decreased digit triplet recognition performance for both participant groups in the midline loudspeaker (p < .001, ηp2 = 0.77). Participants with LUHU had significantly poorer recognition performance relative to peers with normal hearing in the direct condition with noise (p = <.001, M difference = 14.50 rau, 95% CI: 6.46 to 22.54 rau) and the indirect condition with noise (p < .001, M difference = 79.90 rau, 95% CI: 70.79 to 89.00 rau). Furthermore, participants with LUHU had significantly increased response times compared to peers with bilateral normal hearing in the indirect loudspeaker condition with noise (p < .001, M difference = 624 ms, 95% CI: 428 to 801 ms). Results from the subjective ratings indicated that participants with LUHU rated task difficulty as significantly higher (p < .001), their recognition performance as significantly lower (p < .0001), and the hard to think rating as significantly higher (p = .004) than participants with normal hearing for the indirect condition with noise. Differences between groups were evident even when age differences were controlled for statistically.

Given the increased listening effort that children with LUHU can experience in noisy situations, it was consequently important to evaluate the effects of two intervention options, namely a remote microphone system and a contralateral routing of signal (CROS) system, on listening effort in school-aged children with LUHU in Study III. Behavioral (verbal response time measures) and subjective indices of listening effort were employed. Results indicated that relative to the unaided condition, the remote microphone system significantly improved digit triplet recognition in the midline (p < .001, M difference = 61.50 rau, 95% CI = 39.09 to 83.91 rau), direct (p = .035, M difference = 13.58 rau, 95% CI = 0.79 to 26.38 rau), and indirect (p < .001, M difference = 103.45 rau, 95% CI = 92.06 to 114.84 rau) loudspeaker conditions and significantly reduced verbal response times in the midline (p = .038, M difference = -182 ms, 95% CI = -356 to -9 ms) and indirect (p < .001, M difference = -680 ms, 95% CI = -892 to -468 ms) conditions. Compared to the unaided condition, the CROS system significantly improved digit triplet recognition (p < .001, M difference = 41.95 rau, 95% CI = 29.51 to 54.39 rau) and reduced verbal response times (p < .001, M difference = -422 ms, 95% CI = -626 to -218 ms) only in the indirect condition. Consistent with the findings of digit triplet recognition and verbal response times, analyses of the subjective ratings indicated that the remote microphone system yielded more consistent benefits in terms of ease of listening and motivation to complete the listening task for most participants.

Findings of this research project indicate that due consideration should be given to the negative effects of increased listening effort that can be experienced in acoustic challenging situations even for young, normal hearing school-aged children. Increased listening effort can ultimately be detrimental to academic performance. Extending the evaluation of listening effort to the specific population of school-aged children with LUHU, the findings provide valuable baseline data for clinicians to consider the greater listening effort that can be experienced by school-aged children with LUHU and the effect that non-surgical intervention options of personal, ear-level remote microphone systems and CROS hearing aid systems, may have to reduce the listening effort experienced by this population. Reducing listening effort by means of appropriate intervention options may increase successful participation in academic and social situations for children with LUHU. Using self-report questionnaires can be valuable to support findings of behavioral listening effort measures as well as to determine perceived benefit of intervention options for reducing listening effort in school-aged children. Combining results of multiple indices of listening effort may contribute to management and educational plans for children with LUHU.