Understanding how we hear when it's noisy
Physically speaking, most of us would agree there aren’t many positive things about the aging process. Our dependence on reading glasses takes a more permanent turn. Joints become a little less willing to bend without creaking or aching. And we tend to turn the television up a few notches louder and start accusing our friends and family of whispering more in our presence.
Experience, however, is a great equalizer, especially as it relates to hearing loss and our ability to distinguish voices in crowded, noisy and distracting environments. Not only does our brain rely on our ears to understand and process speech, it also relies on information from other senses and past experiences to enhance understanding – something older adults have in spades.
That’s the finding of researchers at Queen’s University who are studying how our brains extract the sound of a single voice in challenging auditory surroundings such as a cocktail party or crowded restaurants. The results of the study led by Dr. Ingrid Johnsrude were presented at the 8th Annual Meeting of the Canadian Association for Neuroscience held in Montreal, Canada May 25-28, 2014.
The research exposed test subjects to muffled or clear speech in both challenging and normal listening environments and studied which areas of the brain were activated in each condition. The research revealed that while older adults had difficulty understanding new voices in a noisy situation, they did not show a decline in the ability to understand familiar voices in the same situation.
They believe that’s because not only do you need to focus on the person you’re talking to in noisy environments, what you understand is influenced by what you’re used to hearing. That means it’s usually easier to hear a familiar voice than that of a stranger.
“We wanted to investigate the glass-half-full side of aging,” Dr. Johnsrude said. “One thing that older people have more of than younger people is experience. I study how the experience of older people, like their familiarity with the voice of their significant other, helps them compensate for age-related declines in other abilities.”
What does age have to do with it, anyway?
Age-related hearing loss is called presbycusis and is one of the most common conditions affecting older adults and the elderly. Typically, presbycusis occurs from gradual changes in the inner ear and affects both ears equally. According to the National Institute on Deafness and Other Communication Disorders (NIDCD), one in three people Americans between the ages of 65 and 74 have hearing loss and nearly half of those older than 75 have difficulty hearing.
Those who spent a lifetime working in a noisy environment like construction or manufacturing may also develop noise-induced hearing loss (NIHL). Both conditions are caused by damage to hair cells in the inner ear, which are responsible for translating the noise our ears collect into electrical impulses and sending them along the auditory nerve to our brain for translation into the sounds we understand. Presbycusis and NIHL are sensorineural in nature, meaning there is permanent damage to the cochlea or nerve pathways from the inner ear to the brain. The good news is this condition can most often be treated successfully with hearing aids.
Untreated hearing loss and cognitive development
While it’s comforting to know familiarity with our significant others helps us cope with physical decline as we age, it’s important to seek treatment if you suspect you have hearing loss. Untreated hearing loss is more than just a nuisance, it can be a safety issue and lead to other health conditions, too. Untreated hearing loss makes it difficult to hear warning signals (such as railroad crossing bells or smoke alarms). It affects the relationship we have with our friends and family, often causing isolation, anxiety and depression.
Other studies indicate untreated hearing loss can cause a variety of cognitive delays and decline. In 2011, a study by Dr. Frank Lin and colleagues at Johns Hopkins University found individuals with mild hearing loss were twice as likely to develop dementia as those with normal hearing. The risk was higher for those with moderate hearing loss (3 times) and severe hearing loss (5 times).
If you suspect you have hearing loss, talk to your primary care physician or an audiologist. They will be able to test your hearing and make recommendations on the best form of treatment based on your age, lifestyle and type of hearing loss.