Results from a recent study of hearing in middle-aged and older adults suggest that hearing loss is not the only factor playing a role as people experience age-related speech comprehension problems. Rather, declines in cognitive skills, particularly memory and processing speed, also contribute.

The research, which was conducted by hearing scientist Karen Helfer at the University of Massachusetts Amherst, 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 during this season when different generations gather around the holiday table.

Helfer’s study tested participants’ ability to understand a same-gender speaker in the presence of one or more background speakers. She says a great deal is known about how people in their 20s and 30s respond to competing speech and even about how adults older than 60 years respond, ‘but ours is one of the very few investigations to study this situation in middle-aged adults, 45 to 59 years old’.

‘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,’ said Helfer.

She and colleagues studied groups of 15 young adults aged 19–28 years, 15 middle-aged 45–59 years, and 15 older adults aged 61–85 years old, who took a number of 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.

Another interesting observation from this work, the researcher adds, is that middle-aged adults frequently complain of having trouble hearing in their daily lives, but when they come in for a test their hearing is normal.

‘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 that 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,’ said Helfer. The 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.

This UMass Amherst project is now actively seeking new study subjects (ages 45 years and older) who would be asked to make two 90-minute to 2-hour visits to a hearing lab on campus. Participants would receive $10 an hour for their time. The work is supported by a 5-year, $1.3 million grant from the NIH’s National Institute for Deafness and Other Communication Disorders.