Impaired frequency selectivity and sensitivity to temporal fine structure, but not envelope cues, in children with mild-to-moderate sensorineural hearing loss

Neural Envelope Processing at Low Frequencies Predicts Speech Understanding of Children With Hearing Loss in Noise and Reverberation

OBJECTIVE

Children with hearing loss experience greater difficulty understanding speech in the presence of noise and reverberation relative to their normal hearing peers despite provision of appropriate amplification. The fidelity of fundamental frequency of voice (f0) encoding-a salient temporal cue for understanding speech in noise-could play a significant role in explaining the variance in abilities among children. However, the nature of deficits in f0 encoding and its relationship with speech understanding are poorly understood. To this end, we evaluated the influence of frequency-specific f0 encoding on speech perception abilities of children with and without hearing loss in the presence of noise and/or reverberation.

METHODS

In 14 school-aged children with sensorineural hearing loss fitted with hearing aids and 29 normal hearing peers, envelope following responses (EFRs) were elicited by the vowel /i/, modified to estimate f0 encoding in low (<1.1 kHz) and higher frequencies simultaneously. EFRs to /i/ were elicited in quiet, in the presence of speech-shaped noise at +5 dB signal to noise ratio, with simulated reverberation time of 0.62 sec, as well as both noise and reverberation. EFRs were recorded using single-channel electroencephalogram between the vertex and the nape while children watched a silent movie with captions. Speech discrimination accuracy was measured using the University of Western Ontario Distinctive Features Differences test in each of the four acoustic conditions. Stimuli for EFR recordings and speech discrimination were presented monaurally.

RESULTS

Both groups of children demonstrated a frequency-dependent dichotomy in the disruption of f0 encoding, as reflected in EFR amplitude and phase coherence. Greater disruption (i.e., lower EFR amplitudes and phase coherence) was evident in EFRs elicited by low frequencies due to noise and greater disruption was evident in EFRs elicited by higher frequencies due to reverberation. Relative to normal hearing peers, children with hearing loss demonstrated: (a) greater disruption of f0 encoding at low frequencies, particularly in the presence of reverberation, and (b) a positive relationship between f0 encoding at low frequencies and speech discrimination in the hardest listening condition (i.e., when both noise and reverberation were present).

CONCLUSIONS

Together, these results provide new evidence for the persistence of suprathreshold temporal processing deficits related to f0 encoding in children despite the provision of appropriate amplification to compensate for hearing loss. These objectively measurable deficits may underlie the greater difficulty experienced by children with hearing loss.

Variability in auditory processing performance is associated with reading difficulties rather than with history of otitis media

The nature and cause of auditory processing deficits in dyslexic individuals have been debated for decades. Auditory processing deficits were argued to be the first step in a causal chain of difficulties, leading to difficulties in speech perception and thereby phonological processing and literacy difficulties. More recently, it has been argued that auditory processing difficulties may not be causally related to language and literacy difficulties. This study compares two groups who have phonological processing impairments for different reasons: dyslexia and a history of otitis media (OM). We compared their discrimination thresholds and response variability to chronological age- and reading age-matched controls, across three auditory processing tasks: frequency discrimination, rise-time discrimination and speech perception. Dyslexic children showed raised frequency discrimination thresholds in comparison with age-matched controls but did not differ from reading age-matched controls or individuals with a history of OM. There were no group differences on speech perception or rise-time tasks. For the dyslexic children, there was an association between phonological awareness and frequency discrimination response variability, but no association with thresholds. These findings are not consistent with a 'causal chain' explanation but could be accounted for within a multiple deficits view of literacy difficulties.

Perception of voice cues in school-age children with hearing aids

The just-noticeable differences (JNDs) of the voice cues of voice pitch (F0) and vocal-tract length (VTL) were measured in school-aged children with bilateral hearing aids and children and adults with normal hearing. The JNDs were larger for hearing-aided than normal-hearing children up to the age of 12 for F0 and into adulthood for all ages for VTL. Age was a significant factor for both groups for F0 JNDs, but only for the hearing-aided group for VTL JNDs. Age of maturation was later for F0 than VTL. Individual JNDs of the two groups largely overlapped for F0, but little for VTL. Hearing thresholds (unaided or aided, 500-400 Hz, overlapping with mid-range speech frequencies) did not correlate with the JNDs. However, extended low-frequency hearing thresholds (unaided, 125-250 Hz, overlapping with voice F0 ranges) correlated with the F0 JNDs. Hence, age and hearing status differentially interact with F0 and VTL perception, and VTL perception seems challenging for hearing-aided children. On the other hand, even children with profound hearing loss could do the task, indicating a hearing aid benefit for voice perception. Given the significant age effect and that for F0 the hearing-aided children seem to be catching up with age-typical development, voice cue perception may continue developing in hearing-aided children.

Features of Cognitive Ability and Central Auditory Processing of Preschool Children With Minimal and Mild Hearing Loss

OBJECTIVE

This study aimed to investigate the current status of cognitive development and central auditory processing development of preschool children with minimal and mild hearing loss (MMHL) in Nanjing, China.

METHOD

We recruited 34 children with MMHL and 45 children with normal hearing (NH). They completed a series of tests, including cognitive tests (i.e., Wechsler Preschool and Primary Scale of Intelligence and Continuous Performance Test), behavioral auditory tests (speech-in-noise [SIN] test and frequency pattern test), and objective electrophysiological audiometry (speech-evoked auditory brainstem response and cortical auditory evoked potential). In addition, teacher evaluations and demographic information and questionnaires completed by parents were collected.

RESULTS

Regarding cognitive ability, statistical differences in the verbal comprehensive index, full-scale intelligence quotient, and abnormal rate of attention test score were found between the MMHL group and the NH group. The children with MMHL performed poorer on the SIN test than the children with NH. As for the auditory electrophysiology of the two groups, the latency and amplitude of some waves of the speech-evoked auditory brainstem response and cortical auditory evoked potential were statistically different between the two groups. We attempted to explore the relationship between some key indicators of auditory processing and some key indicators of cognitive development.

CONCLUSIONS

Children with MMHL are already at increased developmental risk as early as preschool. They are more likely to have problems with attention and verbal comprehension than children with NH. This condition is not compensated with increasing age during the preschool years. The results suggest a possible relationship between the risk of cognitive deficit and divergence of auditory processing.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.22670473.

Differences Between Young and Older Adults in Working Memory and Performance on the Test of Basic Auditory Capabilities†

The Test of Basic Auditory Capabilities (TBAC) is a battery of auditory-discrimination tasks and speech-identification tasks that has been normed on several hundred young normal-hearing adults. Previous research with the TBAC suggested that cognitive function may impact the performance of older adults. Here, we examined differences in performance on several TBAC tasks between a group of 34 young adults with a mean age of 22.5 years (SD = 3.1 years) and a group of 115 older adults with a mean age of 69.2 years (SD = 6.2 years) recruited from the local community. Performance of the young adults was consistent with prior norms for this age group. Not surprisingly, the two groups differed significantly in hearing loss and working memory with the older adults having more hearing loss and poorer working memory than the young adults. The two age groups also differed significantly in performance on six of the nine measures extracted from the TBAC (eight test scores and one average test score) with the older adults consistently performing worse than the young adults. However, when these age-group comparisons were repeated with working memory and hearing loss as covariates, the groups differed in performance on only one of the nine auditory measures from the TBAC. For eight of the nine TBAC measures, working memory was a significant covariate and hearing loss never emerged as a significant factor. Thus, the age-group deficits observed initially on the TBAC most often appeared to be mediated by age-related differences in working memory rather than deficits in auditory processing. The results of these analyses of age-group differences were supported further by linear-regression analyses with each of the 9 TBAC scores serving as the dependent measure and age, hearing loss, and working memory as the predictors. Regression analyses were conducted for the full set of 149 adults and for just the 115 older adults. Working memory again emerged as the predominant factor impacting TBAC performance. It is concluded that working memory should be considered when comparing the performance of young and older adults on auditory tasks, including the TBAC.

Verification of a Mobile Psychoacoustic Test System

Many hearing difficulties can be explained as a loss of audibility, a problem easily detected and treated using standard audiological procedures. Yet, hearing can be much poorer (or more impaired) than audibility predicts because of deficits in the suprathreshold mechanisms that encode the rapidly changing, spectral, temporal, and binaural aspects of the sound. The ability to evaluate these mechanisms requires well-defined stimuli and strict adherence to rigorous psychometric principles. This project reports on the comparison between a laboratory-based and a mobile system's results for psychoacoustic assessment in adult listeners with normal hearing. A description of both systems employed is provided. Psychoacoustic tests include frequency discrimination, amplitude modulation detection, binaural encoding, and temporal gap detection. Results reported by the mobile system were not significantly different from those collected with the laboratory-based system for most of the tests and were consistent with those reported in the literature. The mobile system has the potential to be a feasible option for the assessment of suprathreshold auditory encoding abilities.

Causal Relationship between the Right Auditory Cortex and Speech-Evoked Envelope-Following Response: Evidence from Combined Transcranial Stimulation and Electroencephalography

Speech-evoked envelope-following response (EFR) reflects brain encoding of speech periodicity that serves as a biomarker for pitch and speech perception and various auditory and language disorders. Although EFR is thought to originate from the subcortex, recent research illustrated a right-hemispheric cortical contribution to EFR. However, it is unclear whether this contribution is causal. This study aimed to establish this causality by combining transcranial direct current stimulation (tDCS) and measurement of EFR (pre- and post-tDCS) via scalp-recorded electroencephalography. We applied tDCS over the left and right auditory cortices in right-handed normal-hearing participants and examined whether altering cortical excitability via tDCS causes changes in EFR during monaural listening to speech syllables. We showed significant changes in EFR magnitude when tDCS was applied over the right auditory cortex compared with sham stimulation for the listening ear contralateral to the stimulation site. No such effect was found when tDCS was applied over the left auditory cortex. Crucially, we further observed a hemispheric laterality where aftereffect was significantly greater for tDCS applied over the right than the left auditory cortex in the contralateral ear condition. Our finding thus provides the first evidence that validates the causal relationship between the right auditory cortex and EFR.

Children with hearing loss can predict during sentence processing

Listeners readily anticipate upcoming sentence constituents, however little is known about prediction when the input is suboptimal, such as for children with hearing loss (HL). Here we examined whether children with hearing aids and/or cochlear implants use semantic context to predict upcoming spoken sentence completions. We expected reduced prediction among children with HL, but found they were able to predict similarly to children with normal hearing. This suggests prediction is robust even when input quality is chronically suboptimal, and is compatible with the idea that recent advances in the management of pre-lingual HL may have minimised some of the language processing differences between children with and without HL.

Cortical potentials evoked by tone frequency changes compared to frequency discrimination and speech perception: Thresholds in normal-hearing and hearing-impaired subjects

Frequency discrimination ability varies within the normal hearing population, partially explained by factors such as musical training and age, and it deteriorates with hearing loss. Frequency discrimination, while essential for several auditory tasks, is not routinely measured in clinical setting. This study investigates cortical auditory evoked potentials in response to frequency changes, known as acoustic change complexes (ACCs), and explores their value as a clinically applicable objective measurement of frequency discrimination. In 12 normal-hearing and 13 age-matched hearing-impaired subjects, ACC thresholds were recorded at 4 base frequencies (0.5, 1, 2, 4 kHz) and compared to psychophysically assessed frequency discrimination thresholds. ACC thresholds had a moderate to strong correlation to psychophysical frequency discrimination thresholds. In addition, ACC thresholds increased with hearing loss and higher ACC thresholds were associated with poorer speech perception in noise. The ACC threshold in response to a frequency change therefore holds promise as an objective clinical measurement in hearing impairment, indicative of frequency discrimination ability and related to speech perception. However, recordings as conducted in the current study are relatively time consuming. The current clinical application would be most relevant in cases where behavioral testing is unreliable.

Relationship between sensitivity to temporal fine structure and spoken language abilities in children with mild-to-moderate sensorineural hearing loss

Children with sensorineural hearing loss show considerable variability in spoken language outcomes. The present study tested whether specific deficits in supra-threshold auditory perception might contribute to this variability. In a previous study by Halliday, Rosen, Tuomainen, and Calcus [(2019). J. Acoust. Soc. Am. 146, 4299], children with mild-to-moderate sensorineural hearing loss (MMHL) were shown to perform more poorly than those with normal hearing (NH) on measures designed to assess sensitivity to the temporal fine structure (TFS; the rapid oscillations in the amplitude of narrowband signals over short time intervals). However, they performed within normal limits on measures assessing sensitivity to the envelope (E; the slow fluctuations in the overall amplitude). Here, individual differences in unaided sensitivity to the TFS accounted for significant variance in the spoken language abilities of children with MMHL after controlling for nonverbal intelligence quotient, family history of language difficulties, and hearing loss severity. Aided sensitivity to the TFS and E cues was equally important for children with MMHL, whereas for children with NH, E cues were more important. These findings suggest that deficits in TFS perception may contribute to the variability in spoken language outcomes in children with sensorineural hearing loss.