By Subong Kim, Ph.D.
Many people have trouble understanding speech in noisy places, such as restaurants, classrooms, or crowded rooms. What is especially interesting is that people with similar results on standard hearing tests can still differ greatly in how well they understand speech in noise. In this study, we wanted to better understand why these differences occur.
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We focused on a brain measure called neural signal-to-noise ratio, or neural SNR. In simple terms, neural SNR reflects how strongly the brain responds to the speech a person is trying to hear compared with the background noise.
Participants listened to speech in noise under two conditions. One condition was moderately difficult, while the other was more challenging because the target speech was quieter relative to the background noise.
We also measured two other abilities that could affect listening in noise. First, we measured how the lower part of the auditory system responds to a simple speech sound, the syllable /da/. This gave us information about how clearly speech-related sound information is represented early in the auditory system. Second, we measured speech-based attention, or how well a person can focus on one speaker while ignoring competing speech.
In the moderately difficult listening condition, people whose brains showed a stronger representation of the target speech relative to the background noise also tended to perform better on the speech-in-noise task. We also found that both early auditory processing and the ability to focus attention on target speech were related to neural SNR.
We interpreted this to mean that the brain’s representation of speech in noise may depend on both how well sound information is encoded and how well a listener can focus on the speech they want to hear.
When we looked at these measures together, they explained a meaningful amount of the differences in speech-in-noise performance across participants. This suggests that understanding speech in noise does not depend on just one ability. Instead, it likely depends on several parts of the auditory and attention systems working together.
The results were somewhat different in the more difficult listening condition. In that condition, neural SNR was no longer clearly related to speech-in-noise performance, while speech-based attention was still related to how well participants performed. This may mean that when listening becomes especially difficult, attention becomes particularly important.
As published in Hearing Research in October 2026, overall our findings suggest that differences in speech-in-noise ability may reflect a combination of early auditory processing, attention, and how strongly the brain represents target speech compared with background noise.
Understanding how these factors work together may help explain why some people struggle more than others to follow conversations in noisy everyday environments, even when their standard hearing tests are similar.
A 2022–2023 Emerging Research Grants scientist, Subong Kim, Ph.D., is an assistant professor of audiology in the department of communication sciences and disorders at Montclair State University in New Jersey. The team’s paper, “Cortical speech-in-noise processing reflects subcortical syllable encoding and lexical attention,” appears in Hearing Research in October 2026.
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Overall our findings suggest that differences in speech-in-noise ability may reflect a combination of early auditory processing, attention, and how strongly the brain represents target speech compared with background noise.