Hearing During Echolocation in Whales and Bats

Echolocation comprises an animal sending out signals and listening for the echoes bouncing off objects in the environment. Given the ease of recording outgoing clicks and cries, more information is known about the outgoing signals than what animals hear of the echoes. Loud outgoing signals produce pronounced echoes but also create problems for hearing when the animal immediately attempts to listen for the quiet returning echoes. Recent work measuring hearing with auditory evoked potentials has allowed a new look at what animals hear while they echolocate. Hearing sensation changes due to middle ear muscle contractions during bat vocalization production protect the auditory system from overstimulation and allow better echo hearing. Whale and dolphin hearing sensation levels also change to maximize the hearing of echoes but may operate differently. A number of mechanisms come into play to maximize hearing during echolocation.