Background: People across the age span show increased difficulty hearing speech in the presence of background noise. Developmental deficits in early life could exacerbate it and lead to language difficulties later. Impoverished speech-in-noise (SIN) perception has also been linked to other disorders like autism, where it is hypothesized that this difficulty occurs along with other perceptual impairments. The Frequency-Following response (FFR) is an auditory event-related potential elicited by periodic auditory stimuli that can faithfully phase-lock the spectrotemporal characteristics of the periodic sound wave presented. Considering that disruptions in the FFR has been seen in a wide range of language disorders, this response could emerge as an effective tool to assess this phenomenon. Nevertheless, despite its importance, noise background influence in speech perception has never been investigated in newborns. The present study aims to compare how background noise could modify speech perception in newborns and adults through the analysis of their FFRs.

Method: FFR was recorded in both healthy term newborns (aged <48 hours after birth) and normal-hearing adults (aged 20-35 years). The auditory stimulus was a /da/ syllable with a duration of 170 ms and a fundamental frequency (F0) of 113 Hz, reproduced at 65 dB. The /da/ syllable is divided into two segments: a consonant transition section (10-57 ms) and a steady vowel section (57-170 ms). The noise condition was assessed by playing a Spanish six-talker babble noise at 55 dB. Different FFR parameters were retrieved from the recordings in time and frequency domains for both sections of the stimulus separately.

Results: Results showed that both newborns and adults exhibited larger signal amplitude to the speech stimulus in silence than when presented in noise, albeit newborns obtained consistently lower FFR parameter values than adults. However, the adult group showed greater impairments of speech encoding mechanisms in the noisy condition compared to the newborn group.

Conclusion: Speech encoding in newborns seemed to be less affected by the noise condition than adults, perhaps due to their auditory system only being exposed to attenuated sounds during gestation. This study constitutes one of the first steps towards understanding the development of SIN perception from the first days of life. Detecting FFR impairments in the processing of SIN in an early stage might help to prevent the emergence of future language difficulties, like specific language impairments or dyslexia, or even improve academic experience of healthy individuals.