OBJECTIVE Exploring the specific changes in brain signal variability during healthy aging using functional near-infrared spectroscopy technology.METHODS Twenty-eight young adults and 30 elderly adults were included,and functional near-infrared spectroscopy was used to record the changes in brain blood oxygen and calculate the brain signal variability during the execution of visual-audio dual tasks.RESULTS The brain signal variability of the elderly group was significantly reduced when performing visual-audio dual tasks,especially in the bilateral dorsolateral prefrontal cortex,right Broca,bilateral primary somatosensory cortex,bilateral Wernicke area,bilateral frontopolar area,bilateral primary motor cortex,bilateral somatosensory association cortex,bilateral orbitofrontal area,bilateral pre-motor and supplementary motor cortex.The brain signal variability in the left primary somatosensory cortex(r=-0.385,P=0.043)and right primary somatosensory cortex(r=-0.386,P=0.042)of young adults was negatively correlated with visual reaction time;The brain signal variability in the right somatosensory association cortex(r=-0.371,P=0.044),left pre-motor and supplementary motor cortex(r=-0.393,P=0.032)of elderly adults was negatively correlated with visual reaction time.CONCLUSION Elderly individuals exhibit a significant reduction in neural signal variability within the prefrontal cortex and sensory related cortex,resulting in diminished neural dynamic adaptability that compromises behavioral performance during visual-audio dual tasks.