Effect of Auditory Maturation on the Encoding of a Speech Syllable in the First Days of Life

Abstract

(1) Background: In neonates and infants, the physiological modifications associated with language development are reflected in their Frequency Following Responses (FFRs) in the first few months of life. (2) Objective: This study aimed to test the FFRs of infants in the first 45 days of life in order to evaluate how auditory maturation affects the encoding of a speech syllable. (3) Method: In total, 80 healthy, normal-hearing infants, aged 3 to 45 days old, participated in this study. The sample was divided into three groups: GI, 38 neonates from 3 to 15 days; GII, 25 infants from 16 to 30 days; and GIII, 17 infants from 31 to 45 days. All participants underwent FFR testing. Results: With age, there was a decrease in the latency of all FFR waves, with statistically significant differences among the groups studied for waves V, A, E, F, and O. The mean amplitudes showed an increase, with a statistically significant difference only for wave V. The slope measure increased over the 45 days, with a statistically significant difference between GIII and GI and between GIII and GII. (4) Conclusions: The encoding of a speech sound changes with auditory maturation over the first 45 days of an infant’s life.

Longitudinal trajectories of the neural encoding mechanisms of speech-sound features during the first year of life

“…The FFR has also been explored during the first months of life in several cross-sectional studies with different age periods of interest, as an attempt to describe its typical trajectory along early development. A decrease in neural conduction times and neural phase-locking onset has been already observed at the early age of 45 days (Ferreira et al, 2021), with further shortenings until the age of ten months (Anderson et al, 2015).…”

“…The FFR has also been explored during the first months of life in several cross-sectional studies with different age periods of interest, as an attempt to describe its typical trajectory along early development. A decrease in neural conduction times and neural phase-locking onset has been already observed at the early age of 45 days (Ferreira et al, 2021), with further shortenings until the age of ten months (Anderson et al, 2015). An adult-like voice pitch encoding at birth has also been reported (Arenillas-Alcón et al, 2021; Jeng et al, 2016), with a more robust neural representation with age across the first year of life (Jeng et al, 2010; Ribas-Prats et al, 2023b; Van Dyke et al, 2017).…”

Encoding of speech sounds with frequency-following response in infants with Congenital Zika Syndrome: A case-controlled study

“…In this instance, the outcomes of the frequency-following response (FFR) indicated the presence of all components, albeit with prolonged latency and diminished amplitude, potentially attributable to the reduced synchronization of neuron populations in the correlogram and FFR responses. This damage could be explained, since researchers have proven that the maturation of speech sounds occurs from the initial days of life 14 and depends on central nervous system (CNS) integrity 15 , however, the deprivation of auditory input due to hearing loss can lead to low neural activity.…”