We investigated the impact of both intrinsic and extrinsic cognitive demands on auditory and secondary task performance in older adults with normal hearing (NH) and adults using hearing aids (HAs) in an ecologically relevant listening environment.
Fifteen adults with NH and 15 adults using HAs (60 to 72 years of age) were recruited to perform the “Audiovisual True-to-Life Assessment of Auditory Rehabilitation”-paradigm (AVATAR), which combines an auditory-visual speech-in-noise task with three secondary tasks on either auditory localization or visual short-term memory in a preload multitask paradigm. Intrinsic demands were altered by presenting speech either at equivalent speech accuracy levels of 50% correct (SPIN50%) or equivalent speech-to-noise ratios of +5dB SNR (SPIN+5dB). We manipulated the amount of extrinsic cognitive demands by including one (dual condition) or three secondary tasks (quadruple condition). Performance decrements on the secondary tasks were considered to reflect an increase in resource allocation to speech understanding and thus an increase in listening effort. In addition, we administered a cognitive test battery as well as a questionnaire on self-reported hearing difficulties and subjective measures of effort and motivation.
Speech understanding and secondary task performance on the visual short-term memory task were lower in the SPIN50% condition compared to SPIN+5dB. Whereas speech understanding at SPIN50% was equally high in the dual and quadruple conditions, the quadruple condition resulted in lower secondary task performance on the visual short-term memory task, higher levels of self-reported effort, and lower motivation compared to the dual-task condition. The same was true for experimental conditions at SPIN+5dB. Additionally, adults with NH outperformed adults using HAs on speech understanding, auditory localization, and self-reported hearing abilities, but no group differences were observed on secondary task costs or cognitive measures.
This study showed that, irrespective of the hearing status of the listener, speech performance was not affected by the amount of extrinsic cognitive demands, but was worse and required more effort under conditions with a more negative SNR. Also, increasing the extrinsic cognitive demands resulted in lower performance on one of the secondary tasks, suggesting that more complex listening environments require more effort. Although adults with NH outperformed HA users on speech understanding and auditory localization, the two groups did not differ with respect to secondary task costs.