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Purpose: Prosody perception is an essential component of speech communication and social interaction through which both linguistic and emotional information are conveyed. Considering the importance of the auditory system in processing prosody-related acoustic features, the aim of this review article is to review the effects of hearing impairment on prosody perception in children and adults. It also assesses the performance of hearing assistive devices in restoring prosodic perception., Method: Following a comprehensive online database search, two lines of inquiry were targeted. The first summarizes recent attempts toward determining the effects of hearing loss and interacting factors such as age and cognitive resources on prosody perception. The second analyzes studies reporting beneficial or detrimental impacts of hearing aids, cochlear implants, and bimodal stimulation on prosodic abilities in people with hearing loss., Results: The reviewed studies indicate that hearing-impaired individuals vary widely in perceiving affective and linguistic prosody, depending on factors such as hearing loss severity, chronological age, and cognitive status. In addition, most of the emerging information points to limitations of hearing assistive devices in processing and transmitting the acoustic features of prosody., Conclusions: The existing literature is incomplete in several respects, including the lack of a consensus on how and to what extent hearing prostheses affect prosody perception, especially the linguistic function of prosody, and a gap in assessing prosody under challenging listening situations such as noise. This review article proposes directions that future research could follow to provide a better understanding of prosody processing in those with hearing impairment, which may help health care professionals and designers of assistive technology to develop innovative diagnostic and rehabilitation tools., Supplemental Material: https://doi.org/10.23641/asha.21809772.

Speech production while wearing hearing protectors poses significant challenges due to their occlusion effect and disruption of the Lombard effect. An experiment was conducted with 24 individuals as they read a list of 12 sentences in open ears and while wearing an earmuff in quiet and in four different noises [pink, International Female Fluctuating Masker (IFFM), speech-spectrum noise (SSnoise), and helicopter] at two levels (70 and 85 dBA). An acoustic manikin, fitted or not with an identical protector, served as the target listener. In noise, speech levels decreased when the talkers wore the earmuff but increased when the target listener was fitted with the earmuff. When the earmuff was used by both the talkers and target listener, speech levels were lower by 3-6 dB at the higher noise level compared to when they were both open ears. Speech levels were typically lower, but extended speech intelligibility index estimates were consistently higher, in fluctuating (IFFM, helicopter) than in continuous noises (pink, SSnoise). Talkers' pitch frequency and voice spectrum measurements followed very closely the changes in speech levels, showing no evidence of compensatory voice modifications. Implications of the lower talker speech levels when wearing hearing protectors are discussed in terms of protector selection, training, and individuals with hearing loss.

Background: Room reverberation alters the acoustical properties of the speech signals reaching our ears, affecting speech understanding. Therefore, it is important to understand the consequences of reverberation on auditory processing. In perceptual studies, the direct sound and early reflections of reverberated speech have been found to constitute useful energy, whereas the late reflections constitute detrimental energy., Purpose: This study investigated how various components (direct sound versus early reflections versus late reflections) of the reverberated speech are encoded in the auditory system using the speech-evoked auditory brainstem response (ABR)., Research Design: Speech-evoked ABRs were recorded using reverberant stimuli created as a result of the convolution between an ongoing synthetic vowel /a/ and each of the following room impulse response (RIR) components: direct sound, early reflections, late reflections, and full reverberation. Four stimuli were produced: direct component, early component, late component, and full component., Study Sample: Twelve participants with normal hearing participated in this study., Data Collection and Analysis: Waves V and A amplitudes and latencies as well as envelope-following response (EFR) and fine structure frequency-following response (FFR) amplitudes of the speech-evoked ABR were evaluated separately with one-way repeated measures analysis of variances to determine the effect of stimulus. Post hoc comparisons using Tukey's honestly significant difference test were performed to assess significant differences between pairs of stimulus conditions., Results: For waves V and A amplitudes, a significant difference or trend toward significance was found between direct and late components, between direct and full components, and between early and late components. For waves V and A latencies, significant differences were found between direct and late components, between direct and full components, between early and late components, and between early and full components. For the EFR and FFR amplitudes, a significant difference or trend toward significance was found between direct and late components, and between early and late components. Moreover, eight, three, and one participant reported the early, full, and late stimuli, respectively, to be the most perceptually similar to the direct stimulus., Conclusions: The stimuli that are acoustically most similar (direct and early) result in electrophysiological responses that are not significantly different, whereas the stimuli that are acoustically most different (direct and late, early and late) result in responses that are significantly different across all response measures. These findings provide insights toward the understanding of the effects of the different components of the RIRs on auditory processing of speech., (American Academy of Audiology)

This study introduces an improved method to investigate the effects of reverberation using the speech-evoked auditory brainstem response (ABR) that more realistically captures the influence of self- and overlap-masking induced by room reverberation. Speech-evoked ABR was measured under three acoustic scenarios: anechoic, mild reverberation with dominance of early reflections, and severe reverberation with dominance of late reverberation. Responses were significantly weaker and had longer latencies with severe reverberation relative to anechoic and mild reverberation. Although larger responses and shorter latencies were observed with mild reverberation than anechoic, possibly due to early reflections, these reached significance in only one of six ABR response measures.

Objectives: This study investigated speech auditory brainstem responses (speech ABR) with variants of a synthetic vowel in quiet and in background noise. Its objectives were to study the noise robustness of the brainstem response at the fundamental frequency F0 and at the first formant F1, evaluate how the resolved/unresolved harmonics regions in speech contribute to the response at F0, and investigate the origin of the response at F0 to resolved and unresolved harmonics in speech., Design: In total, 18 normal-hearing subjects (11 women, aged 18-33 years) participated in this study. Speech ABRs were recorded using variants of a 300 msec formant-synthesized /a/ vowel in quiet and in white noise. The first experiment employed three variants containing the first three formants F1 to F3, F1 only, and F2 and F3 only with relative formant levels following those reported in the literature. The second experiment employed three variants containing F1 only, F2 only, and F3 only, with the formants equalized to the same level and the signal-to-noise ratio (SNR) maintained at -5 dB. Overall response latency was estimated, and the amplitude and local SNR of the envelope following response at F0 and of the frequency following response at F1 were compared for the different stimulus variants in quiet and in noise., Results: The response at F0 was more robust to noise than that at F1. There were no statistically significant differences in the response at F0 caused by the three stimulus variants in both experiments in quiet. However, the response at F0 with the variant dominated by resolved harmonics was more robust to noise than the response at F0 with the stimulus variants dominated by unresolved harmonics. The latencies of the responses in all cases were very similar in quiet, but the responses at F0 due to resolved and unresolved harmonics combined nonlinearly when both were present in the stimulus., Conclusions: Speech ABR has been suggested as a marker of central auditory processing. The results of this study support earlier work on the differential susceptibility to noise of the F0 and F1 components of the evoked response. In the case of F0, the results support the view that in speech, the pitch of resolved harmonics and that of unresolved harmonics are processed in different but interacting pathways that converge in the upper brainstem. Pitch plays an important role in speech perception, and speech ABR can offer a window into the neural extraction of the pitch of speech and how it may change with hearing impairment.

The objective of this study is to investigate whether Speech Evoked Potentials (SpEPs), which are auditory brainstem responses to speech stimuli, contain information that can be used to distinguish different speech stimuli. Previous studies on brainstem SpEPs show that they contain valuable information about auditory neural processing. As such, SpEPs may be useful for the diagnosis of central auditory processing disorders and language disability, particularly in children. In this work, we examine the spectral amplitude information of both the Envelope Following Response, which is dominated by spectral components at the fundamental (F0) and its harmonics, and Frequency Following Response, which is dominated by spectral components in the region of the first formant (F1), of SpEPs in response to the five English language vowels (\a\,\e\,\ae\,\i\,\u\). Using spectral amplitude features, a classification accuracy of 78.3% is obtained with a linear discriminant analysis classifier. Classification of SpEPs demonstrates that brainstem neural responses in the region of F0 and F1 contain valuable information for discriminating vowels. This result provides an insight into human auditory processing of speech, and may help develop improved methods for objectively assessing central hearing impairment.

We investigated whether pitch-synchronous neural activity could be recorded in humans, with a natural vowel and a vowel in which the fundamental frequency was suppressed. Small variations of speech periodicity were detected in the evoked responses using a fine structure spectrograph (FSS). A significant response (P < 0.001) was measured in all seven normal subjects even when the fundamental frequency was suppressed, and it very accurately tracked the acoustic pitch contour (normalized mean absolute error < 0.57%). Small variations in speech periodicity, which humans can detect, are therefore available to the perceptual system as pitch-synchronous neural firing. These findings suggest that the measurement of pitch-evoked responses may be a viable tool for objective speech audiometry.

This study introduces an improved method to investigate the effects of reverberation using the speech-evoked auditory brainstem response (ABR) that more realistically captures the influence of self- and overlap-masking induced by room reverberation. Speech-evoked ABR was measured under three acoustic scenarios: anechoic, mild reverberation with dominance of early reflections, and severe reverberation with dominance of late reverberation. Responses were significantly weaker and had longer latencies with severe reverberation relative to anechoic and mild reverberation. Although larger responses and shorter latencies were observed with mild reverberation than anechoic, possibly due to early reflections, these reached significance in only one of six ABR response measures. [ABSTRACT FROM AUTHOR]

This study investigated whether speech-evoked auditory brainstem responses (speech ABRs) can be automatically separated into distinct classes. With five English synthetic vowels, the speech ABRs were classified using linear discriminant analysis based on features contained in the transient onset response, the sustained envelope following response (EFR), and the sustained frequency following response (FFR). EFR contains components mainly at frequencies well below the first formant, while the FFR has more energy around the first formant. Accuracies of 83.33% were obtained for combined EFR and FFR features and 38.33% were obtained for transient response features. The EFR features performed relatively well with a classification accuracy of 70.83% despite the belief that vowel discrimination is primarily dependent on the formants. The FFR features obtained a lower accuracy of 59.58% possibly because the second formant is not well represented in all the responses. Moreover, the classification accuracy based on the transient features exceeded chance level which indicates that the initial response transients contain vowel specific information. The results of this study will be useful in a proposed application of speech ABR to objective hearing aid fitting, if the separation of the brain’s responses to different vowels is found to be correlated with perceptual discrimination. [ABSTRACT FROM AUTHOR]

Objectives: To study level effects in the encoding of four vowels in normal hearing adults using the envelope and spectral frequency following response (eFFR and sFFR). We hypothesized that F0, F1 and their neighboring harmonics would grow with increasing level. Material and methods: 19 subjects (8F, 11M, 20-35 yrs) were recorded with four 100 ms vowel stimuli with F0=100 Hz (F1: /a/=700 Hz, /e/=600 Hz,/d/=500 Hz,/u/=300 Hz) at four levels (55, 65, 75, and 85 dBA). eFFR and sFFR spectral amplitudes for each vowel and level were analyzed. Results: Significant effects of level exist at F0 in the eFFR and F1 in the sFFR (p<0.01 in all cases). The combined harmonics show effects oflevel (p<0.001 in all cases), as well as significant pairwise comparisons between most levels. Conclusions: Effects of level exist in the encoding of the speech eFFR and sFFR. 'Ihe eFFR shows increasing spectral richness via the growth of the harmonics of F0 but not at F0 itself, while the sFFR shows a pattern of growth at FI and its neighboring harmonics. [ABSTRACT FROM AUTHOR]