Estimate the time required for the sound to travel a distance of 10 m, be detected by the ear, travel as a nerve impulse to the brain, be processed, then travel as a nerve signal for muscle action back to an arm, and finally cause a muscle contraction. nerve impulses travel at a speed of about 120 m/s in humans. distances traveled by the nerve impulses are 10 cm to the brain and then 75 cm from the brain to the arm. assume that the detection time of the ear and the reaction time of the muscle are about 50 ms and that the brain processing time adds a further 100 ms.