Difficulty understanding speech in noisy environments may be more than a frustrating consequence of aging. New research suggests it could serve as an early indicator of brain changes associated with cognitive vulnerability, even before measurable cognitive decline becomes apparent.
In a longitudinal study published in JAMA Otolaryngology–Head & Neck Surgery, researchers found that older adults with poorer speech-in-noise performance experienced faster thinning of brain regions involved in speech processing and higher-order cognitive functions over a three-year period. Notably, these associations were independent of traditional hearing test results and hearing aid use.
The findings add to a growing body of evidence suggesting that how well a person processes speech in challenging listening environments may provide important insights into brain health beyond what can be learned from pure-tone audiometry alone.
Speech-in-Noise Performance Linked to Brain Structure Changes
The study followed 312 cognitively normal older adults in Australia, with an average age of 73.5 years. Participants underwent hearing evaluations, cognitive testing, and magnetic resonance imaging (MRI) at baseline and again three years later.
The investigators examined three hearing-related factors:
- Peripheral hearing loss measured through audiometric thresholds
- Speech-in-noise ability measured using the Listening in Spatialized Noise-Sentences (LiSN-S) test, and
- Hearing aid use.
Over the three-year follow-up period, age-related brain atrophy was observed throughout the cohort, which the researchers noted is consistent with normal aging. However, participants who performed more poorly on the speech-in-noise test at baseline showed significantly faster cortical thinning in several temporoparietal brain regions.
These regions included the inferior parietal cortex, precuneus, middle temporal cortex, and superior temporal sulcus—areas involved in speech comprehension, auditory attention, language processing, and the integration of auditory information with higher cognitive functions.
According to the researchers, “poorer baseline speech-in-noise performance was associated with faster cortical thinning” in these regions, even after accounting for age, sex, hearing thresholds, and hearing aid use.
In contrast, traditional measures of hearing loss were not associated with accelerated brain atrophy over time.
Traditional Hearing Tests Did Not Predict Longitudinal Decline
One of the study’s most notable findings was the distinction between peripheral hearing loss and central auditory processing.
Participants with hearing loss showed expected differences in hearing thresholds and speech-in-noise performance. Those with untreated hearing loss also demonstrated thinner superior temporal cortex regions at baseline compared to participants with normal hearing.
However, when researchers examined changes over time, pure-tone hearing thresholds did not predict future cortical thinning. Similarly, hearing aid use was not associated with significant differences in brain volume or cortical thickness trajectories during the study period.
The researchers reported that “peripheral hearing loss and hearing aid use were not associated with longitudinal neurostructural change or cognitive decline.”
While some trends suggested possible preservation of certain brain structures among long-term hearing aid users, these findings did not remain statistically significant after correction for multiple comparisons.
The investigators cautioned that the relatively short follow-up period and modest number of hearing aid users may have limited their ability to detect potential long-term neuroprotective effects of amplification.
These findings differ somewhat from recent studies suggesting hearing intervention may reduce cognitive decline risk. The authors noted that structural brain changes, hearing outcomes, and cognitive outcomes may not always follow the same timeline, particularly in cognitively healthy populations.
What the Findings Mean for Hearing Care and Cognitive Health
Perhaps the most clinically relevant finding is that speech-in-noise testing appeared to identify neural vulnerability before measurable cognitive decline occurred.
Although participants with poorer speech-in-noise performance demonstrated greater cortical thinning, the study did not find corresponding declines in global cognitive scores during the three-year observation period.
The researchers believe this may be because neurodegenerative processes often begin years before cognitive symptoms become detectable using standard screening tools.
The study concluded that “speech-in-noise impairment may serve as an early behavioral marker of neural vulnerability preceding measurable cognitive decline.”
For hearing care professionals, the findings reinforce the value of including speech-in-noise assessments as part of routine evaluations, particularly for older adults who report listening difficulties despite relatively mild hearing loss.
Traditional audiograms remain essential for diagnosing peripheral hearing loss, but they may not fully capture changes occurring within central auditory networks and related brain systems.
The researchers emphasized that central auditory processing may provide a more sensitive measure of brain health than pure-tone thresholds. They suggest that speech-in-noise performance could eventually play a role in identifying individuals at increased risk for future cognitive decline, though additional long-term studies will be needed to determine how these brain changes relate to dementia and other neurodegenerative conditions.
While the study does not suggest that speech-in-noise difficulties directly cause brain atrophy, it provides new evidence that these listening challenges may reflect early changes occurring within speech-processing networks of the aging brain.
Reference:
Zanin J, McNeil JJ, Rance G. Speech-in-Noise Ability and Longitudinal Cortical Thinning in Speech-Processing Networks. JAMA Otolaryngol Head Neck Surg. Published online May 28, 2026. doi:10.1001/jamaoto.2026.1050
Source: JAMA Otolaryngology
