The effect of background babble on working memory in young and middle-aged adults.

BACKGROUND

Background noise has been found to negatively affect working memory. Numerous studies have also found that older adults perform more poorly on working memory tasks than young adults (YA). Hearing status has often been a confounding factor in older individuals. Therefore, it would be beneficial to investigate working memory functions in adverse listening conditions early in the aging process (i.e., middle-age), when hearing function is relatively unaffected.

PURPOSE

The focus of this study was to determine the influence of background babble on working memory in YA and middle-aged adults (MA) with normal hearing.

RESEARCH DESIGN

Before testing was begun, we established that all participants could correctly identify words in a degraded experimental testing environment with 100% accuracy. Then, the participants listened to lists composed of five pairs of words in quiet and in 20-talker babble. After the final word pair, the participants were cued with the first word of one of the previous five word pairs. The participants were required to write down the second word of the pair. The percent correct scores for each of the five serial positions were analyzed comparing the two listening conditions for YA and MA. Ten YA and ten MA with normal hearing between 250-8000 Hz and a score of at least 26/30 on the Mini-Mental State Examination participated in the study. As different cognitive processes are used for initial, middle, and final serial positions, averaged scores were obtained for Positions 2 and 3 and for Positions 4 and 5. Subsequently, repeated-measures analyses of variance (ANOVAs) were conducted on mean scores of correctly recalled word pairs with serial positions (initial, middle, and final) and listening condition (quiet, babble) as the within-participant variables and age group (YA, MA) as the between-participant independent variable. This OMNIBUS repeated-measures ANOVA was then followed up with separate repeated-measures ANOVAS for the initial, middle, and final positions.

RESULTS

Correct recall scores were lower for early positions compared with the latter positions, irrespective of listening condition. For Position 1, YA-but not MA-performed significantly better in babble than in quiet. For the middle positions (Positions 2 and 3), MA performed significantly more poorly than the YA irrespective of listening condition. For the final positions (Positions 4 and 5), no age differences or effects of listening condition were found.

CONCLUSIONS

The results indicate that both YA and MA have trouble recalling earlier pieces of information in quiet and in babble. However, MA exhibited significantly poorer recall scores than YA in babble for Position 1, which suggest that cognitive processes related to memory encoding and retrieval are different in background babble for MA and YA.