Cortical-evoked potentials reflect speech-in-noise perception in children

Abstract

Children are known to be particularly vulnerable to the effects of noise on speech perception, and it is commonly acknowledged that failure of central auditory processes can lead to these difficulties with speech-in-noise (SIN) perception. However, little is known about the mechanistic relationship between central processes and the perception of SIN. Our aims were twofold: to examine the effects of noise on the central encoding of speech through measurement of cortical event-related potentials and to examine the relationship between cortical processing and behavioral indices of SIN perception. We recorded cortical responses to the speech syllable [da] in quiet and multi-talker babble noise in 32 children with a broad range of SIN perception. Outcomes suggest inordinate effects of noise on auditory function in the bottom SIN perceivers compared with the top perceivers. The cortical amplitudes in the top SIN group remained stable between conditions, whereas amplitudes increased significantly in the bottom SIN group, suggesting a developmental central processing impairment in the bottom perceivers that may contribute to difficulties in encoding and perceiving speech in challenging listening environments.

© 2010 The Authors. European Journal of Neuroscience © 2010 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

Figures

Figure 1

Top: The acoustic waveform of the target stimulus [da]. The formant transition and vowel regions are bracketed. Bottom: The spectrogram (stronger amplitudes represented with brighter colors). The boundary between the consonant-vowel formant transition and the steady-state vowel portion of the syllable is marked by a dashed white line.

Figure 2

Effects of noise in top vs. bottom SIN groups. Headplots demonstrate greater neural activity in the noise condition in the bottom SIN group in the 175 to 225 ms. There were significant effects of noise for the Fz channel in the bottom SIN group range (F1,14 = 4.861, p = 0.045) but not in the top SIN group (F1,14 = 0.699, p = 0.471).

Figure 3

Effects of noise on cortical-evoked responses to speech in grand averages across all subjects (N=32). The P1 component disappears in noise in both GFP and the Fz channel. In addition, the GFP waveform shows more focused activity in the noise condition.

Figure 4

Differences between top and bottom SIN groups in the quiet and noise conditions. Greater amplitudes are noted in the poor SIN group compared to the good group in both GFP and the Fz channel in noise but not in quiet. Top: Grand average waveforms in quiet show no significant differences in the Fz channel (A) or GFP (B) between the bottom SIN group (black) and the top SIN group (gray). Middle: Grand average waveforms in the noise condition demonstrate higher N2 amplitudes in the bottom SIN group (black) compared to the top SIN group (gray) for both the Fz channel (C) and GFP (D). Bottom right (E): Bar graphs demonstrated group differences in the noise condition bottom SIN > top SIN (p < 0.05). Bottom left (F): A significant interaction between the quiet and noise conditions for the two groups in GFP (p < 0.05) with bottom SIN > top SIN only in noise.

Figure 5

Relationships between N2 magnitudes and SIN perception. Scatterplots of the relationships between HINT-Front raw scores and N2 magnitudes in the noise condition in GFP and the Fz channel, demonstrating that better SIN perception is related to smaller N2 magnitudes in noise.