Stride time variability is associated with falls among seniors. Adding a secondary task to walking can be detrimental to old adults' gait. Beat perception measured from beat alignment task (BAT) was correlated with better synchronization to the beat in rhythmic auditory cueing (RAC). Also, patients with Parkinson's disease showed to benefit from RAC. It is unknown whether walking performance improved across cognitive load and whether beat perception could benefit RAC in healthy old adults.

Participants were 11 young adults and 5 old adults without cognitive, motor, and sensory impairments. In session 1, participants completed background tasks including BAT. In session 2, they performed walking and listening tasks separately and simultaneously. The complexities of dual-tasks were 1) Simple condition, synchronization of walking to low tones, 2) Moderate condition, to high and low tones, and 3) Complex condition, to high and low while responding to a particular series of tones via a clicker. 

For outcome measures, a negative dual-task cost of stride time variability indicates a facilitation and a positive value, detriments. BAT was scored as the number of correct responses. Overall, older adults showed greater dual-task cost of stride time variability, whereas young adults showed negligible costs. Notably, young adults showed a dual-task facilitation in the Complex condition, supporting that alleviating the internal focus on movement could benefit walking. For old adults, auditory-motor dual-tasks were detrimental due to the allocation of attentional resources. Performance on the BAT differently impacted old adults and young adults across conditions. 

In conclusion, older adults had more variability during dual-task walking compared to walking at preferred speed, therefore did not benefit from RAC. Young adults performed the best in the most complex dual-task. BAT affected the dual-task cost of stride time variability more in older than younger adults.