Explain the textbook echo method for measuring sound speed and the timing correction.

Solution & explanation

Measure distance d to a large reflector. A single echo delay is a round trip, so v = 2d/t. To reduce reaction error, synchronize repeated claps to successive echoes and time n complete echo intervals: v = 2dn/Δt. Count intervals, not merely endpoints; ten claps do not automatically imply ten intervals. Repeat and average, using an isolated clear reflector.