The influence of phoneme contexts on adaptation in vowel‐evoked envelope following responses

Easwar, Vijayalakshmi; Chung, Lauren

doi:10.1111/ejn.15768

Cited by 5 publications

(10 citation statements)

References 47 publications

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“…They used speech-shaped noise as the preceding masker for EFRs elicited by /a/ in /da/ and demonstrated delayed peak latencies in masked conditions. The present study results are, however, inconsistent with Easwar et al (2021) who found no statistically significant effects of the surrounding context on EFRs elicited by a wide range of vowels. The discrepancy between the present study and Easwar et al (2021) could be due to the characteristics of the context as well as the EFR stimulus.…”

Section: Discussioncontrasting

confidence: 99%

“…The present study results are, however, inconsistent with Easwar et al (2021) who found no statistically significant effects of the surrounding context on EFRs elicited by a wide range of vowels. The discrepancy between the present study and Easwar et al (2021) could be due to the characteristics of the context as well as the EFR stimulus. The contexts were higher in level and longer in duration in the present study, which may have led to increased chances of forward masking (Lasky & Rupert 1982; Kramer & Teas 1982).…”

Section: Discussioncontrasting

confidence: 99%

“…The discrepancy in findings between these two studies in terms of the sensitivity of EFRs to preceding context acoustics may arise from the level and spectral characteristics of the masker, and differences in level between the masker and the stimulus. While in the former study, the level of the speech-shaped noise masker and EFR stimulus remained constant at 75 dB SPL and 70 dB ppeSPL, respectively, the level of consonants in the latter study varied as per natural production; relative to the level of vowel stimuli, the surrounding consonants in Easwar et al (2021) were 0.2 to 19.2 dB lower. Further, these two studies also likely varied in the context or masker spectra; the speech-shaped masker used in the former study likely had a relatively wider bandwidth compared to the consonants used in the latter study.…”

Section: Introductionmentioning

confidence: 87%

“…When preceded by a 100-msec-long speech-shaped noise with masker-stimulus intervals ranging from 4 to 64 msec, responses to the /a/ in /da/ were delayed in latency (Hodge et al 2018) (amplitude not reported). In contrast, no effects of the consonant context (/hVd/, /sVt/, /zVf/, and /ʒVv/, where V refers to the EFR-eliciting vowel stimulus) were found on the amplitude of EFRs evoked by a wide range of naturally spoken vowels despite lack of any time interval between the preceding consonants and the EFR-eliciting vowel (Easwar et al 2021). The discrepancy in findings between these two studies in terms of the sensitivity of EFRs to preceding context acoustics may arise from the level and spectral characteristics of the masker, and differences in level between the masker and the stimulus.…”

Section: Introductionmentioning

confidence: 90%

“…The real and imaginary EFR components were independently averaged over the vowel duration to a single complex number, which was further used to estimate EFR amplitude. Although one limitation of averaging over the entire vowel duration is the inability to observe changes in EFRs over time, we used the entire window for consistency with prior vowel-evoked EFR studies that varied preceding phoneme contexts (e.g., Choi et al 2013; Easwar et al 2021). Residual noise was estimated by averaging EEG amplitude at 14 frequency bins surrounding the response f 0 to determine satisfactory recording conditions.…”

Section: Methodsmentioning

confidence: 99%

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Sensitivity of Vowel-Evoked Envelope Following Responses to Spectra and Level of Preceding Phoneme Context

2022

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Objective: Vowel-evoked envelope following responses (EFRs) could be a useful noninvasive tool for evaluating neural activity phase-locked to the fundamental frequency of voice (f 0 ). Vowel-evoked EFRs are often elicited by vowels in consonant-vowel syllables or words. Considering neural activity is susceptible to temporal masking, EFR characteristics elicited by the same vowel may vary with the features of the preceding phoneme. To this end, the objective of the present study was to evaluate the influence of the spectral and level characteristics of the preceding phoneme context on vowel-evoked EFRs.Design: EFRs were elicited by a male-spoken /i/ (stimulus; duration = 350 msec), modified to elicit two EFRs, one from the region of the first formant (F1) and one from the second and higher formants (F2+). The stimulus, presented at 65 dB SPL, was preceded by one of the four contexts: /∫/, /m/, /i/ or a silent gap of duration equal to that of the stimulus. The level of the context phonemes was either 50 or 80 dB SPL, 15 dB lower and higher than the level of the stimulus /i/. In a control condition, EFRs to the stimulus /i/ were elicited in isolation without any preceding phoneme contexts. The stimulus and the contexts were presented monaurally to a randomly chosen test ear in 21 young adults with normal hearing. EFRs were recorded using single-channel electroencephalogram between the vertex and the nape. Results:A repeated measures analysis of variance indicated a significant three-way interaction between context type (/∫/, /i/, /m/, silent gap), level (50, 80 dB SPL), and EFR-eliciting formant (F1, F2+). Post hoc analyses indicated no influence of the preceding phoneme context on F1-elicited EFRs. Relative to a silent gap as the preceding context, F2+-elicited EFRs were attenuated by /∫/ and /m/ presented at 50 and 80 dB SPL, as well as by /i/ presented at 80 dB SPL. The average attenuation ranged from 14.9 to 27.9 nV. When the context phonemes were presented at matched levels of 50 or 80 dB SPL, F2+-elicited EFRs were most often attenuated when preceded by /∫/. At 80 dB SPL, relative to the silent preceding gap, the average attenuation was 15.7 nV, and at 50 dB SPL, relative to the preceding context phoneme /i/, the average attenuation was 17.2 nV. Conclusion:EFRs elicited by the second and higher formants of /i/ are sensitive to the spectral and level characteristics of the preceding phoneme context. Such sensitivity, measured as an attenuation in the present study, may influence the comparison of EFRs elicited by the same vowel in different consonant-vowel syllables or words. However, the degree of attenuation with realistic context levels exceeded the minimum measurable change only 12% of the time. Although the impact of the preceding context is statistically significant, it is likely to be clinically insignificant a majority of the time.

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Section: Discussioncontrasting

confidence: 99%

Section: Discussioncontrasting

confidence: 99%

Section: Introductionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 90%

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations

Sensitivity of Vowel-Evoked Envelope Following Responses to Spectra and Level of Preceding Phoneme Context

2022

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

Easwar,

Peng,

Boothalingam

et al. 2024

Ear &Amp; Hearing

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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.

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The influence of phoneme contexts on adaptation in vowel‐evoked envelope following responses

Easwar

Chung

2022

Eur J of Neuroscience

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Repeated stimulus presentation leads to neural adaptation and consequent amplitude reduction in vowel-evoked envelope following responses (EFRs)-a response that reflects neural activity phase-locked to envelope periodicity.EFRs are elicited by vowels presented in isolation or in the context of other phonemes such as consonants in syllables. While context phonemes could exert some forward influence on vowel-evoked EFRs, they may reduce the degree of adaptation. Here, we evaluated whether the properties of context phonemes between consecutive vowel stimuli influence adaptation. EFRs were elicited by the low-frequency first formant (resolved harmonics) and middleto-high-frequency second and higher formants (unresolved harmonics) of a male-spoken /i/ when the presence, number and predictability of context phonemes (/s/, /a/, / Ð / and /u/) between vowel repetitions varied. Monitored over four iterations of /i/, adaptation was evident only for EFRs elicited by the unresolved harmonics. EFRs elicited by the unresolved harmonics decreased in amplitude by $16-20 nV (10%-17%) after the first presentation of /i/ and remained stable thereafter. EFR adaptation was reduced by the presence of a context phoneme, but the reduction did not change with their number or predictability. The presence of a context phoneme, however, attenuated EFRs by a degree similar to that caused by adaptation ($21-23 nV). Such a trade-off in the short-and long-term influence of context phonemes suggests that the benefit of interleaving EFR-eliciting vowels with other context phonemes depends on whether the use of consonant-vowel syllables is critical to improve the validity of EFR applications.

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The influence of phoneme contexts on adaptation in vowel‐evoked envelope following responses

Cited by 5 publications

References 47 publications

Sensitivity of Vowel-Evoked Envelope Following Responses to Spectra and Level of Preceding Phoneme Context

Sensitivity of Vowel-Evoked Envelope Following Responses to Spectra and Level of Preceding Phoneme Context

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

The influence of phoneme contexts on adaptation in vowel‐evoked envelope following responses

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