by Dr. Terence Miranda
Hearing is inextricably linked to cognition. Audiologists will say that the ears collect sound but it is the brain that hears. There is substantial research that highlights a connection between untreated hearing loss and cognitive disorders. More recent research is showing that improving hearing reduces the risk of cognitive decline. Keeping our hearing healthy is an important part of helping to keep our brain in an optimal state.
Because we can not fully close our ears like we can do with our eyes, the brain is constantly receiving and processing sounds. This processing keeps the auditory centres of the brain engaged and ‘exercised’. When we hear, the brain chooses to pay attention to some sounds (e.g. conversations) and decides not to pay attention to other sounds (e.g. the hum of traffic).
We all have a certain amount of cognitive capacity or ‘brain power’. This cognitive resource is of course limited and the amount we have at a given time depends on a whole myriad of factors, for example, on how fatigued we are. When we have untreated hearing loss, we use our cognitive resources, as well as our vision, to fill in the blanks of what our ears are not giving us. When we have a conversation, it is of course necessary to hear before we can understand the content. A hearing deficiency commands cognitive resources first and what brain power is left over can then be used to process, remember, recall, think ahead, draw analogies, create and understand jokes, etc.
Research has shown that there is a significantly higher incidence of cognitive disorder in people with untreated hearing loss. For example, individuals with hearing loss between the ages of 45-65 have been shown to have from 2-5 times the risk of reduced cognition and dementia, depending on the severity of the hearing loss (Lin et al., 2011; Livingston et al, 2020). More recent research (e.g. Jiang et al., 2023) is beginning to show that when hearing loss is treated, cognitive performance is significantly improved.
The primary advantage of correcting milder degrees of hearing loss is the potential cognitive benefit. When missing sounds are filled in with assistive devices such as hearing aids, it reduces demands on limited cognitive resources which can then be deployed for higher order cognitive tasks.