When listening to recorded speech that is somewhat unclear, resembling the sounds people with cochlear implants hear, both older and younger adults use contextual cues to enhance their understanding, according to a recent study in the Journal of Speech, Language, and Hearing Research.
The study found that both age groups use context to a similar degree.
“Even though, as we age, we have more risk of problems with both auditory processing and some aspects of cognition, we found that aging doesn’t change our ability to make use of context in understanding speech,” said Aaron Moberly, M.D., a co-author and an otolaryngologist at the Bill Wilkerson Center at Vanderbilt University Medical Center.
“Aging doesn’t change our ability to make use of context in understanding speech.”
“Older adults were able to make up for some of those deficits as well as younger people did when hearing speech that was not clear,” he added.
Research With Normal-hearing People
The findings have implications for post-implantation training of cochlear implant recipients.
“For years, we’ve observed that some cochlear implant users seem to take advantage of linguistic context to understand speech better than others do,” said senior author Terrin Tamati, Ph.D., of the Cochlear Implant Cognition and Communication Lab at Vanderbilt.
To study these processes in a more homogeneous group of listeners, the researchers worked with normal-hearing adults who listened to speech that was manipulated to replicate the speech sounds heard by someone with an implant.
An Innovative Approach
“Working with normal-hearing people gives us more flexibility to study the challenges that recipients face, using a controlled study design,” Tamati said.
Exposing normal-hearing participants to degraded speech is a somewhat unusual approach to research in this field, she said. “But it gets us more flexibility; it provides us with more resources to get to the bottom of the problem faced by people with implants.”
Comprehension and Cognition Tested
In total, 88 adults with normal hearing participated in the study; 45 were between the ages of 18 and 35 years, and 39 were between 50 and 85. All had normal general language proficiency.
Participants were tested for two hours in a sound-proof booth. They completed two sentence-recognition tasks. One task involved listening to semantically meaningful, ordinary sentences. The second task involved irregular sentences that used correct structure but made no sense. (“The deep buckle walked the old crowd,” was one example.)
Participants also underwent a battery of neurocognitive and linguistic tests. These assessed working-memory measures, speed of lexical access, and vocabulary knowledge.
Both Age Groups Used Context Similarly
For meaningful sentences, the mean sentence recognition scores were 74.6 percent and 66.5 percent for younger normal-hearing and older normal-hearing adults, respectively. For the irregular sentences, the mean sentence recognition scores were 47.3 percent and 39.2 percent for younger and older participants, respectively.
“Although the findings indicate poorer speech recognition skills among the older adults as compared to younger ones, the relative benefit of the sentences’ context was not different,” Moberly said.
A person with a cochlear implant sitting with their family in a noisy restaurant is usually going to struggle with understanding, Tamati explained.
“We think that one way for cochlear implant users to understand the degraded speech signals they hear is to use available linguistic resources, including context.
“If you’re speaking another language and not quite sure, you might notice that having a lot of context can help you figure things out, and that is true for cochlear implant users, too.”
Context Can Support Comprehension
Findings may help improve auditory therapy for cochlear implant recipients.
After placement of a cochlear implant, aural rehabilitation takes place to teach users how to listen to and interpret the sounds being conveyed.
“Can we teach people to fill in the blanks better? Can they be trained in abilities or in efficiency? That would be the clinical ramification of this work. Maybe we can improve their ability to function in the real world,” Moberly said. To date, auditory therapy has not specifically included training in the use of context cues.
“Our field recognizes a need for more individualized types of training. Some people will respond to some kinds of support and others to something different,” he added. “We want to identify individualized problems that contribute to issues people have with the implants, and also their strengths. Then we can individualize treatments.”