Sound Effects on Standing Postural Strategies in the Elderly via Frequency Analysis Approach

Abstract

Sound and sound frequency could improve postural sway in the elderly. The power spectrum intervals of the center of pressure (COP) displacement are associated with different postural regulations, which could be revealed by frequency analysis. The aim of the study was to investigate the effects of sound on dual-tasking postural control and conduct frequency analysis to distinguish postural regulations in the elderly. Fifteen young and 15 older healthy participants were instructed to stand on a force platform and performed the Purdue Pegboard test while hearing 50 dB sounds with sound frequencies of 250 Hz, 1000 Hz, 4000 Hz, or no sound. The total excursion, velocity, sway area, and power spectrum of low-, medium-, and high-frequency bands of the COP displacement were calculated in the anterior–posterior and medial–lateral directions. The percentages of low-frequency and medium-frequency bands in both directions were significantly different between with and without sound conditions, but not affected by sound frequency. Older adults showed a smaller percentage of low-frequency, larger percentage of medium-frequency, larger total COP excursion, and faster velocity in the medial–lateral direction. The outcome of the study supports the frequency analysis approach in evaluating sound effects on postural strategies in dual-tasking and reveals older adults utilize vestibular regulation as the primary postural strategy when the dual-task required visual attention.

The effects of Tai Chi on standing balance control in older adults may be attributed to the improvement of sensory reweighting and complexity rather than reduced sway velocity or amplitude

“…According to the result of frequency analysis, the higher moderate-frequency band and lower very-low-frequency band were observed in the TC group, which demonstrated that the TC group relies on more proprioception and less on the vestibular system in standing balance control than the control group. It has been found that older adults utilize vestibular regulation as the primary postural strategy in dual-task standing compared with young adults (Lee et al, 2020 ), which demonstrated that older adults adopted the control strategy with larger vestibular contribution in standing balance compared with young adults. In addition, older patients with neck pain relied more on the vestibular system and less on proprioception in standing balance control with and without vision than older adults with no neck pain (Quek et al, 2014 ), patients with cervical spondylotic myelopathy exhibited lower proprioceptive contribution and higher vestibular contribution under the eyes-open stance (Lin et al, 2019 ), and older adults with long-term Tai Chi practice showed better balance control after vestibular stimulation than the older control group (Tsang and Hui-Chan, 2006 ).…”