The Effect of Signal to Noise Ratio on Cortical Auditory–Evoked Potentials Elicited to Speech Stimuli in Infants and Adults With Normal Hearing
Bibliographic record
Abstract
OBJECTIVES: Identification and discrimination of speech sounds in noisy environments is challenging for adults and even more so for infants and children. Behavioral studies consistently report maturational differences in the influence that signal to noise ratio (SNR) and masker type have on speech processing; however, few studies have investigated the neural mechanisms underlying these differences at the level of the auditory cortex. In the present study, we investigated the effect of different SNRs on speech-evoked cortical auditory-evoked potentials (CAEPs) in infants and adults with normal hearing. DESIGN: A total of 10 adults (mean age 24.1 years) and 15 infants (mean age 30.7 weeks), all with normal hearing, were included in the data analyses. CAEPs were evoked to /m/ and /t/ speech stimuli (duration: 79 ms) presented at 75 dB SPL in the sound field with a jittered interstimulus interval of 1000-1200 ms. Each of the stimuli were presented in quiet and in the presence of white noise (SNRs of 10, 15, and 20 dB). Amplitude and latency measures were compared for P1, N1, and P2 for adults and for the large positivity (P) and following negativity (N: N250 and/or N450) for infants elicited in quiet and across SNR conditions. RESULTS: Infant P-N responses to /t/ showed no statistically significant amplitude and latency effects across SNR conditions; in contrast, infant CAEPs to /m/ were greatly reduced in amplitude and delayed in latency. Responses were more frequently absent for SNRs of 20 dB or less. Adult P1-N1-P2 responses were present for all SNRs for /t/ and most SNRs for /m/ (two adults had no responses to /m/ for SNR 10); significant effects of SNR were found for P1, N1, and P2 amplitude and latencies. CONCLUSIONS: The findings of the present study support that SNR effects on CAEP amplitudes and latencies in infants cannot be generalized across different types of speech stimuli and cannot be predicted from adult data. These findings also suggest that factors other than energetic masking are contributing to the immaturities in the SNR effects for infants. How these CAEP findings relate to an infant's capacity to process speech-in-noise perceptually has yet to be established; however, we can be confident that the presence of CAEPs to a speech stimulus in noise means that the stimulus is detected at the level of the auditory cortex. The absence of a response should be interpreted with caution as further studies are needed to investigate a range of different speech stimuli and SNRs, in conjunction with behavioral measures, to confirm that infant CAEPs do indeed reflect functional auditory capacity to process speech stimuli in noise.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".