To assess the sensitivity of statistical indicators used for the objective detection of speech-evoked envelope following responses (EFRs) in infants and adults.
Twenty-three adults and 21 infants with normal hearing participated in this study. A modified/susa∫i/speech token was presented at 65 dB SPL monoaurally. Presentation level in infants was corrected using in-ear measurements. EFRs were recorded between high forehead and ipsilateral mastoid. Statistical post-processing was completed using F-test, Magnitude-Square Coherence, Rayleigh test, Rayleigh-Moore test, and Hotelling’s T2 test. Logistic regression models assessed the sensitivity of each statistical indicator in both infants and adults as a function of testing duration.
The Rayleigh-Moore and Rayleigh tests were the most sensitive statistical indicators for speech-evoked EFR detection in infants. Comparatively, Magnitude-Square Coherence and Hotelling’s T2 also provide clinical benefit for infants in all conditions after ~30 minutes of testing, whereas the F-test failed to detect responses to EFRs elicited by vowels with accuracy greater than chance. In contrast, the F-test was the most sensitive for vowel-elicited response detection for adults in short tests (<10 minute) and performed comparatively with the Rayleigh-Moore and Rayleigh test during longer test durations. Decreased sensitivity was observed in infants relative to adults across all testing durations and statistical indicators, but the effects were largest in low frequency stimuli and seemed to be mostly, but not wholly, caused by differences in response amplitude.
The choice of statistical indicator significantly impacts the sensitivity of speech-evoked EFR detection. In both groups and for all stimuli, the Rayleigh test and Rayleigh-Moore tests have high sensitivity. Differences in EFR detection are present between infants and adults regardless of statistical indicator; however, these effects are largest for low-frequency EFR stimuli and for amplitude-based statistical indicators.