Effect of competing noise on cortical auditory evoked potentials elicited by speech sounds in 7- to 25-year-old listeners.

Child listeners have particular difficulty with speech perception when competing speech noise is present; this challenge is often attributed to their immature top-down processing abilities. The purpose of this study was to determine if the effects of competing speech noise on speech-sound processing vary with age. Cortical auditory evoked potentials (CAEPs) were measured during an active speech-syllable discrimination task in 58 normal-hearing participants (age 7-25 years). Speech syllables were presented in quiet and embedded in competing speech noise (4-talker babble, +15 dB signal-to-noise ratio; SNR). While noise was expected to similarly reduce amplitude and delay latencies of N1 and P2 peaks in all listeners, it was hypothesized that effects of noise on the P3b peak would be inversely related to age due to the maturation of top-down processing abilities throughout childhood. Consistent with previous work, results showed that a +15 dB SNR reduces amplitudes and delays latencies of CAEPs for listeners of all ages, affecting speech-sound processing, delaying stimulus evaluation, and causing a reduction in behavioral speech-sound discrimination. Contrary to expectations, findings suggest that competing speech noise at a +15 dB SNR may have similar effects on various stages of speech-sound processing for listeners of all ages. Future research directions should examine how more difficult listening conditions (poorer SNRs) might affect results across ages.