Attention to Speech and Music in Young Children with Bilateral Cochlear Implants: A Pupillometry Study

Low-frequency pitch coding: relationships with speech-in-noise and music perception by pediatric populations with typical hearing and cochlear implants

PURPOSE

This study aimed to investigate the effects of low frequency (LF) pitch perception on speech-in-noise and music perception performance by children with cochlear implants (CIC) and typical hearing (THC). Moreover, the relationships between speech-in-noise and music perception as well as the effects of demographic and audiological factors on present research outcomes were studied.

METHODS

The sample consisted of 22 CIC and 20 THC (7-10 years). Harmonic intonation (HI) and disharmonic intonation (DI) tests were used to assess LF pitch perception. Speech perception in quiet (WRSq)/noise (WRSn + 10) were tested with the Italian bisyllabic words for pediatric populations. The Gordon test was used to evaluate music perception (rhythm, melody, harmony, and overall).

RESULTS

CIC/THC performance comparisons for LF pitch, speech-in-noise, and all music measures except harmony revealed statistically significant differences with large effect sizes. For the CI group, HI showed statistically significant correlations with melody discrimination. Melody/total Gordon scores were significantly correlated with WRSn + 10. For the overall group, HI/DI showed significant correlations with all music perception measures and WRSn + 10. Hearing thresholds showed significant effects on HI/DI scores. Hearing thresholds and WRSn + 10 scores were significantly correlated; both revealed significant effects on all music perception scores. CI age had significant effects on WRSn + 10, harmony, and total Gordon scores (p < 0.05).

CONCLUSION

Such findings confirmed the significant effects of LF pitch perception on complex listening performance. Significant speech-in-noise and music perception correlations were as promising as results from recent studies indicating significant positive effects of music training on speech-in-noise recognition in CIC.

The Influence of Hearing Loss on the Pupil Response to Degraded Speech

PURPOSE

Current evidence regarding the influence of hearing loss on the pupil response elicited by speech perception is inconsistent. This might be partially due to confounding effects of age. This study aimed to compare pupil responses in age-matched groups of normal-hearing (NH) and hard of hearing (HH) listeners during listening to speech.

METHOD

We tested the baseline pupil size and mean and peak pupil dilation response of 17 NH participants (Mage = 46 years; age range: 20-62 years) and 17 HH participants (Mage = 45 years; age range: 20-63 years) who were pairwise matched on age and educational level. Participants performed three speech perception tasks at a 50% intelligibility level: noise-vocoded speech and speech masked with either stationary noise or interfering speech. They also listened to speech presented in quiet.

RESULTS

Hearing loss was associated with poorer speech perception, except for noise-vocoded speech. In contrast to NH participants, performance of HH participants did not improve across trials for the interfering speech condition, and it decreased for speech in stationary noise. HH participants had a smaller mean pupil dilation in degraded speech conditions compared to NH participants, but not for speech in quiet. They also had a steeper decline in the baseline pupil size across trials. The baseline pupil size was smaller for noise-vocoded speech as compared to the other conditions. The normalized data showed an additional group effect on the baseline pupil response.

CONCLUSIONS

Hearing loss is associated with a smaller pupil response and steeper decline in baseline pupil size during the perception of degraded speech. This suggests difficulties of the HH participants to sustain their effort investment and performance across the test session.

Cortical responses correlate with speech performance in pre-lingually deaf cochlear implant children

Introduction

Cochlear implantation is currently the most successful intervention for severe-to-profound sensorineural hearing loss, particularly in deaf infants and children. Nonetheless, there remains a significant degree of variability in the outcomes of CI post-implantation. The purpose of this study was to understand the cortical correlates of the variability in speech outcomes with a cochlear implant in pre-lingually deaf children using functional near-infrared spectroscopy (fNIRS), an emerging brain-imaging technique.

Methods

In this experiment, cortical activities when processing visual speech and two levels of auditory speech, including auditory speech in quiet and in noise with signal-to-noise ratios of 10 dB, were examined in 38 CI recipients with pre-lingual deafness and 36 normally hearing children whose age and sex matched CI users. The HOPE corpus (a corpus of Mandarin sentences) was used to generate speech stimuli. The regions of interest (ROIs) for the fNIRS measurements were fronto-temporal-parietal networks involved in language processing, including bilateral superior temporal gyrus, left inferior frontal gyrus, and bilateral inferior parietal lobes.

Results

The fNIRS results confirmed and extended findings previously reported in the neuroimaging literature. Firstly, cortical responses of superior temporal gyrus to both auditory and visual speech in CI users were directly correlated to auditory speech perception scores, with the strongest positive association between the levels of cross-modal reorganization and CI outcome. Secondly, compared to NH controls, CI users, particularly those with good speech perception, showed larger cortical activation in the left inferior frontal gyrus in response to all speech stimuli used in the experiment.

Discussion

In conclusion, cross-modal activation to visual speech in the auditory cortex of pre-lingually deaf CI children may be at least one of the neural bases of highly variable CI performance due to its beneficial effects for speech understanding, thus supporting the prediction and assessment of CI outcomes in clinic. Additionally, cortical activation of the left inferior frontal gyrus may be a cortical marker for effortful listening.