Study Links Eye Movements to Effortful Listening and Hearing Loss

As people age, approximately 40% of them will experience some form of hearing loss. While this age-related hearing loss is most associated with adults over the age of 65, it can start occurring earlier, even in one’s 40s or 50s.

The challenge lies in the fact that existing diagnostic methods may not be sensitive enough to detect early signs of hearing loss, particularly when it involves difficulties in understanding speech in noisy or crowded environments. Researchers are thus working to develop more effective techniques to detect subtle forms of hearing loss before they become irreversible. 

In a recent study published in The Journal of Neuroscience, two neuroscientists at the Rotman Research Institute in Canada explored the relationship between effortful listening and eye movements. They found that when young adults put more effort into hearing speech, their eye movements tend to decrease. 

The conventional method for diagnosing hearing loss is through pure-tone audiometry, which involves listening to pure tones at different sound levels to determine the hearing threshold—the point at which a sound becomes barely audible. However, this method may not effectively capture early signs of hearing loss, particularly those related to speech perception in noisy environments. 

To address this limitation, researchers are investigating additional diagnostic tools that can capture more subtle aspects of hearing. One approach involves examining physiological signs that indicate a person is exerting greater effort to understand speech in challenging conditions, potentially signaling early hearing loss. One commonly studied physiological response related to effortful listening is changes in pupil size, measured using pupillometry.

Pupil size tends to increase when individuals engage in cognitive tasks, and recent research has shown that it also increases during effortful listening, such as when trying to comprehend speech in noisy environments. However, measuring pupil size during a hearing test can be problematic due to its sensitivity to changes in light and the angle of the pupil relative to the measuring camera. 

To address these limitations, researchers conducted experiments with young adults aged 18 to 35 to determine whether changes in eye movements could serve as an alternative indicator of effortful listening. Participants listened to sentences and spoken stories while their eye movements were tracked. The study found that under more challenging listening conditions with significant background noise, participants exhibited decreased eye movements, as indicated by longer fixation durations and reduced gaze dispersion. 

These findings suggest that recording eye movements may provide a valuable tool for assessing listening effort, which could aid in the early detection of hearing problems. Researchers aim to further explore the relationship between eye movements and effortful listening, particularly in older adults who are more likely to experience age-related hearing loss.

Additionally, this approach could help evaluate the effectiveness of hearing aids in reducing listening efforts for individuals with hearing loss. While this research is promising, further studies are needed to fully understand the nuances of listening effort and how eye movements can be used as a reliable diagnostic tool for hearing loss, particularly in clinical settings.