New studies show that hearing loss can lead to changes in the brain. The brain’s ability to change is referred to as neuroplasticity. In early childhood, neuroplasticity is particularly important as it is the foundation for learning and acquiring different skills. Neuroplasticity usually works in our favor, but there are some situations when that is not the case. Dr. Anu Sharma, director of a clinical laboratory at the University of Colorado, and her colleagues suggest that the portion of the brain devoted to hearing, the auditory cortex, can become reorganized when someone develops hearing loss.
The researchers placed electrodes on the head to record the electrical activity in the brain that occurs when someone is listening to sound. When a hearing loss is present, there is reduced and degraded neural stimulation in the auditory cortex. Because the auditory cortex is used less for sound processing, other areas of the brain move into this vacant real estate. Dr. Sharma found that areas once used for processing speech and language in the auditory cortex may become reorganized to process visual or touch information due to neuroplasticity. This means that the quality of auditory processing in the brain is decreased.
This might seem obviously unfavorable to us; however, the brain sees it as an efficient use of unused neural connections. Evidence of this reorganization does not only occur in extreme cases of long-term profound deafness, but also in adults with lesser degrees of hearing loss and as soon as three months after the start of a hearing loss. This finding means that a mild hearing loss is not a mild problem. Evidence indicates that with these changes, the ability to understand speech is severely impacted. It becomes more difficult to follow conversations in noisy situations, such as restaurants or family gatherings. A mild hearing loss may not cause degraded neural stimulation in the auditory cortex, but there is definitely reduced stimulation that will lead the brain to gradually reorganize neural connections.
Many adults with hearing difficulties wait several years on average before seeking intervention. Hearing loss is never normal, regardless of how old someone is, and should always be taken seriously. The longer someone lives with an unmanaged hearing loss, even if it is mild, the more neuroplasticity works to make use of the unused neural connections in the brain.
Thus, when the time comes that someone finally decides to seek hearing healthcare, the process of adapting to and having success with hearing technology can be longer and more difficult. Once the brain starts receiving sound stimulation again, it must work more to reverse the changes made to the auditory cortex.
In light of Dr. Sharma’s findings, diagnosis and intervention should occur very soon after the first indications of a possible hearing loss, regardless of its severity, to protect against reorganization of the brain. Chicago Hearing Care recommends hearing screenings for adults, as we know that early diagnosis can lead to successful intervention. Research has shown that to help ensure the auditory cortex is receiving appropriate neural stimulation from sounds, patients must be successful hearing aid users who consistently use their devices. In other words, the best way to take care of your hearing health is to take care of any difficulties you may notice on the early side rather than toughing it out.
Campbell, J., & Sharma, A. (2013). Compensatory changes in cortical resource allocation in adults with hearing loss. Frontiers in Systems Neuroscience, 7, 1-9.
Sharma, A., & Glick, H. (2016). Cross-Modal Re-Organization in Clinical Populations with Hearing Loss. Brain Sciences, 1-12.
Written by Vienet Romero, Au.D. Student & Alejandra Ullauri, Au.D.