Researchers at Mass General Brigham say they have identified potential objective biomarkers for tinnitus severity by tracking pupil dilation and subtle, involuntary facial movements while people listen to everyday sounds. The work, published in Science Translational Medicine, aims to address a long-standing problem in tinnitus research: severity is typically judged by questionnaires rather than physiological measures.
Tinnitus is commonly described as persistent phantom sound, such as ringing, buzzing, or clicking, and it is widespread in the general population. For many people it is a manageable nuisance, but a smaller group experiences debilitating distress that can disrupt sleep, concentration, and mental health.
Signals tied to threat response
The team focused on the sympathetic nervous system, which governs the body’s fight, flight, or freeze response, to look for outward indicators of distress. They examined whether tinnitus-related distress might be reflected in arousal signals that are visible in the eyes and face.
To test the idea, researchers recruited 97 participants with normal hearing, including 47 with varying levels of tinnitus and sound sensitivity, and 50 control volunteers. Participants listened to pleasant, neutral, and unpleasant sounds while being recorded on video and monitored for pupil changes.
AI helps detect tiny facial changes
Using AI-powered video analysis, the study detected rapid micro-movements in areas such as the cheeks, eyebrows, and nostrils, and found they were associated with self-reported tinnitus distress. When these facial signals were combined with pupil dilation data, the model’s ability to predict severity improved.
People with severe tinnitus showed unusually large pupil dilation across all sound types, while their facial responses were more muted. By contrast, controls and participants with less bothersome tinnitus tended to show stronger pupil and facial reactions mainly to the most unpleasant sounds.
Why this could matter for trials
The researchers argue that objective readouts could make placebo-controlled studies easier to design and interpret, helping the field evaluate treatments more rigorously. They also suggest the approach could potentially be adapted to more accessible, clinic-friendly tools if validated further.
The team noted key limitations, including the need to exclude many people who often have complex tinnitus, such as those with hearing loss, older age, or significant mental health comorbidities. Future studies are expected to test whether the biomarkers hold up in broader, higher-risk populations and in real-world clinical settings.
Researchers involved in the work say they are now exploring how these biomarkers could support therapy development, including approaches that pair neural stimulation with software-based treatment environments. The broader goal is to measure not just the sound people perceive, but the distress response that makes tinnitus disabling for some patients.
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