Helfer's study suggests that subtle cognitive changes affect the ability to understand speech in certain situations rather than a hearing loss.
In this research, Helfer, an expert in aging and speech communication, studied the effect of hearing loss and cognitive abilities in middle-aged and older adults as they experienced a situation called “competing speech,” commonly encountered, for example, when different generations gather around the holiday table. Helfer is a faculty member in the Department of Communication Disorders in the School of Public Health and Health Sciences.
She and colleagues studied groups of 15 young adults 19 to 28 years old, 15 middle-aged 45 to 59 years old, and 15 older adults 61 to 85 years old who took several cognitive tests plus a hearing test, and listened to a spoken message under different competing speech conditions, then were asked to repeat a target sentence from the message.
Helfer says, “I think people assume that having difficulty hearing another speaker in the presence of competing speech is just a matter of hearing loss, but we found that it isn’t that simple. It’s also related to what’s going on in the brain, such as age-related memory changes and processing speed. There are subtle changes going on in addition to hearing loss, and they’re related to how the brain is processing sounds.”
“So clinically, we get middle-aged people coming in for a hearing test and we send them away, telling them they have normal hearing. But they know they’re having trouble in the real world, they report a lot of difficulty hearing in their daily lives. Our study suggests that what’s really going on is they have subtle cognitive changes affecting their ability to understand speech in certain situations.”
Helfer says people use a kind of shorthand for this and say they have “trouble hearing,” when actually they hear just fine. What they have is trouble understanding. Her study found that middle-aged and older adults have particular difficulty understanding when there is one background competing message, a situation that is quite easy for younger adults. “It takes a lot of brain power to listen to one message in a noisy environment or in a place where there’s more than one person talking,” she says.
“This is one of the first studies in middle-aged people using this type of difficult speech perception task. We don’t know a whole lot about how middle-aged people function in these situations.” Results are expected to appear in the Journal of the Acoustical Society of America.
Helfer is quick to point out that this age-related comprehension problem is not an indication that people are noting the onset of dementia, but only that they have normal, age-related cognitive changes. “Almost everybody experiences them to some extent.”
The work is supported by a five-year, $1.3 million grant from the NIH’s National Institute for Deafness and Other Communication Disorders.