# Neural speech encoding advantages associated with higher socioeconomic status extend to noise conditions with differential susceptibility

## TL;DR

Higher socioeconomic status is linked to better neural speech encoding in noise, suggesting long-term benefits from early-life experiences.

## Contribution

The study reveals that socioeconomic status influences neural susceptibility to noise, extending beyond quiet conditions.

## Key findings

- Higher-SES individuals show smaller timing delays and preserved fidelity in noisy speech encoding.
- Neural advantages in higher-SES groups are reflected in larger response magnitudes across speech segments.
- Behavioral SPiN performance is predicted by neural timing and correlation metrics, not SES alone.

## Abstract

Speech perception in noise (SPiN) relies on precise neural encoding of periodic speech cues, which can be assessed using the frequency-following response (FFR). The robustness and fidelity of this encoding vary with maturation, environmental factors, and life experiences. Socioeconomic status (SES), a major contextual determinant of these influences, has been associated with more consistent and higher-quality FFRs in higher-SES individuals. However, it remains unclear whether SES-related advantages in quiet extend to noise. The primary aim was to determine whether SES predicts susceptibility to noise-related degradation in neural encoding, and a secondary aim was to examine whether SES-linked neural differences correspond to behavioral or self-reported SPiN performance.

Seventy higher-education students with normal hearing were classified into low- and high-SES groups based on maternal education. Speech-evoked FFRs to a 170-ms synthetic /da/ were recorded in quiet and in +10 dB SNR babble. Neural timing, magnitude, and fidelity measures were analyzed. Behavioral SPiN was assessed using a monosyllabic adaptive speech-recognition-threshold task, and self-reported SPiN with the SSQ12. Linear mixed-effects models were used to examine SES effects and their modulation by noise on FFR parameters, and ordinary least-squares regressions were used to test whether these FFR metrics predicted behavioral and self-reported SPiN performance.

Significant interactions between SES and noise indicated differential neural susceptibility to degradation, with higher-SES participants showing smaller noise-related delays in onset and transition timing and reduced declines in fidelity. Larger response magnitudes were also observed in the higher-SES group across segments. Behavioral SPiN showed no consistent group differences, although onset-latency and stimulus-to-response correlation predicted performance. No significant associations were detected for self-reported SPiN.

Neural findings indicate that socioeconomic background shapes long-term susceptibility to noise, with higher-SES individuals exhibiting smaller timing delays in both onset and mid-syllabic encoding and more preserved neural fidelity. These advantages may arise from differences in subcortical and cortical phase-locked activity, reflecting neural patterns shaped over development. Maternal education may serve as a proxy for early-life conditions shaped by environmental factors and life experiences during sensitive periods when neural encoding is highly malleable, leaving durable imprints into adulthood.