Human Hearing in the Underwater Environment

Hearing is a key sense that informs us about our environment. The cues we obtain from sounds grab our attention, allow us to communicate, and warn us of danger. Human hearing has evolved to detect sounds in air. As a result, anyone who has tried snorkeling or Scuba diving or have put their head underwater in a bathtub has noticed that the world sounds very different. With ears underwater, sounds seem quieter, as though the listener has cotton stuffed in their ears. Moreover, in air, when one hears a sound, one can usually tell if it is coming from the left or right and, to a lesser degree, if it is from the front or back. Underwater, although a diver can hear a boat’s engine, identifying where the sound is coming from is challenging. This is because early terrestrial vertebrates evolved to hear well in air, and these adaptations are not the same as those needed for the underwater hearing abilities possessed by aquatic ancestors.