Examining speech perception in noise and cognitive functions in the elderly.

PURPOSE

The purpose of this study was to investigate the relationship of cognitive functions (i.e., working memory [WM]) and speech recognition against different background maskers in older individuals.

METHOD

Speech reception thresholds (SRTs) were determined using a matrix-sentence test. Unmodulated noise, modulated noise (International Collegium for Rehabilitative Audiology [ICRA] noise 5-250), and speech fragments (International Speech Test Signal [ISTS]) were used as background maskers. Verbal WM was assessed using the Verbal Learning and Memory Test (VLMT; Helmstaedter & Durwen, 1990). Measurements were conducted with 14 normal-hearing older individuals and a control group of 12 normal-hearing young listeners.

RESULTS

Despite their normal hearing ability, the young listeners outperformed the older individuals in all background maskers. These differences were largest for the modulated maskers. SRTs were significantly correlated with the scores of the VLMT. A linear regression model also included WM as the only significant predictor variable.

CONCLUSIONS

The results support the assumption that WM plays an important role for speech understanding and that it might have impact on results obtained using speech audiometry. Thus, an individual's WM capacity should be considered with aural diagnosis and rehabilitation. The VLMT proved to be a clinically applicable test for WM. Further cognitive functions important with speech understanding are currently being investigated within the SAKoLA (Sprachaudiometrie und kognitive Leistungen im Alter [Speech Audiometry and Cognitive Functions in the Elderly]) project.