Chapter 15, Problem 6CQ

Harbor seals, like many animals, determine the direction from which a sound is coming by sensing the difference in arrival times at their two ears. A small difference in arrival times means that the object is in front of the seal; a larger difference means it is to the left or right. There is a minimum time difference that a seal can sense, and this leads to a limitation on a seal’s direction sense. Seals can distinguish between two sounds that come from directions 3° apart in air, but this increases to 9° in water. Explain why you would expect a seal’s directional discrimination to be worse in water than in air.