Kathy Pichora-Fuller – k.pichora.fuller@utoronto.ca
Department of Psychology, University of Toronto,
3359 Mississauga Road,
Mississauga, Ontario, CANADA L5L 1C6

Sherri Smith – Sherri.Smith@va.gov
Audiologic Rehabilitation Laboratory, Veterans Affairs Medical Center,
Mountain Home, Tennessee, UNITED STATES 37684

Popular version of paper 1pSC2 Effects of age, hearing loss and linguistic complexity on listening effort as measured by working memory span
Presented Monday afternoon, May 18, 2015 (Session: Listening Effort II)
169th ASA Meeting, Pittsburgh

Understanding conversation in noisy everyday situations can be a challenge for listeners, especially individuals who are older and/or hard-of-hearing. Listening in some everyday situations (e.g., at dinner parties) can be so challenging that people might even decide that they would rather stay home than go out. Eventually, avoiding these situations can damage relationships with family and friends and reduce enjoyment of and participation in activities. What are the reasons for these difficulties and why are some people affected more than other people?

How easy or challenging it is to listen may vary from person to person because some people have better hearing abilities and/or cognitive abilities compared to other people. The hearing abilities of some people may be affected by the degree or type of their hearing loss. The cognitive abilities of some people, for example how well they can attend to and remember what they have heard, can also affect how easy it is for them to follow conversation in challenging listening situations. In addition to hearing abilities, cognitive abilities seem to be particularly relevant because in many everyday listening situations people need to listen to more than one person talking at the same time and/or they may need to listen while doing something else such as driving a car or crossing a busy street. The auditory demands that a listener faces in a situation increase as background noise becomes louder or as more interfering sounds combine with each other. The cognitive demands in a situation increase when listeners need to keep track of more people talking or to divide their attention as they try to do more tasks at the same time. Both auditory and cognitive demands could result in the situation becoming very challenging and these demands may even totally overload a listener.

One way to measure information overload is to see how much a person remembers after they have completed a set of tasks. For several decades, cognitive psychologists have been interested in ‘working memory’, or a person’s limited capacity to process information while doing tasks and to remember information after the tasks have been completed. Like a bank account, the more cognitive capacity is spent on processing information while doing tasks, the less cognitive capacity will remain available for remembering and using the information later. Importantly, some people have bigger working memories than other people and people who have a bigger working memory are usually better at understanding written and spoken language. Indeed, many researchers have measured working memory span for reading (i.e., a task involving the processing and recall of visual information) to minimize ‘contamination’ from the effects of hearing loss that might be a problem if they measured working memory span for listening. However, variations in difficulty due to hearing loss may be critically important in assessing how the demands of listening affect different individuals when they are trying to understand speech in noise. Some researchers have studied the effects of the acoustical properties of speech and interfering noises on listening, but less is known about how variations in the type of language materials (words, sentences, stories) might alter listening demands for people who have hearing loss. Therefore, to learn more about why some people cope better when listening to conversation in noise, we need to discover how both their auditory and their cognitive abilities come into play during everyday listening for a range of spoken materials.

We predicted that speech understanding would be more highly associated with working memory span for listening than with listening span for reading, especially when more realistic language materials are used to measure speech understanding. To test these predictions, we conducted listening and reading tests of working memory and we also measured memory abilities using five other measures (three auditory memory tests and two visual memory tests). Speech understanding was measured with six tests (two tests with words, one in quiet and one in noise; three tests with sentences, one in quiet and two in noise; one test with stories in quiet). The tests of speech understanding using words and sentences were selected from typical clinical tests and involved simple immediate repetition of the words or sentences that were heard. The test using stories has been used in laboratory research and involved comprehension questions after the end of the story. Three groups with 24 people in each group were tested: one group of younger adults (mean age = 23.5 years) with normal hearing and two groups of older adults with hearing loss (one group with mean age = 66.3 years and the other group with mean age 74.3 years).

There was a wide range in performance on the listening test of working memory, but performance on the reading test of working memory was more limited and poorer. Overall, there was a significant correlation between the results on the reading and listening working memory measures. However, when correlations were conducted for each of the three groups separately, the correlation reached significance only for the oldest listeners with hearing loss; this group had lower mean scores on both tests. Surprisingly, for all three groups, there were no significant correlations among the working memory and speech understanding measures. To further investigate this surprising result, a factor analysis was conducted. The results of the factor analysis suggest that there was one factor including age, hearing test results and performance on speech understanding measures when the speech-understanding task was simply to repeat words or sentences – these seem to reflect auditory abilities. In addition, separate factors were found for performance on the speech understanding measures involving the comprehension of discourse or the use of semantic context in sentences – these seem to reflect linguistic abilities. Importantly, the majority of the memory measures were distinct from both kinds of speech understanding measures, and also a more basic and less cognitively demanding memory measure involving only the repetition of sets of numbers. Taken together, these findings suggest that working memory measures reflect differences between people in cognitive abilities that are distinct from those tapped by the sorts of simple measures of hearing and speech understanding that have been used in the clinic. Above and beyond current clinical tests, by testing working memory, especially listening working memory, useful information could be gained about why some people cope better than others in everyday challenging listening situations.

tags: age, hearing, memory, linguistics, speech