Neurons in the inferior colliculus of echolocating bats responded well to two stimuli presented in close temporal sequence. Favorable recovery of responsiveness was seen with stimuli having durations, intensities, and interpulse intervals similar to the natural biosonar signals reaching the ears during the various phases of echolocation. Some units responded to a subthreshold simulated echo but only when preceded by a loud initial pulse. These units appear to be specialized for echo-detection.