A strategy used by bats to avoid interfering with each other’s echolocation signals is reported in a paper published this week in Communications Biology. This strategy could have implications for sonar or radar research.
Bats use echolocation to hunt and navigate in darkness and must be able to distinguish their own signals from other bats flying in the same group. How bats avoid acoustical interference in this scenario, known as the ‘cocktail party problem’, is not completely understood.
Kazuma Hase and colleagues directly measured the echolocation behaviour of Eastern bent-wing bats (Miniopterus fuliginosus) using miniature microphones mounted on the bats’ backs. The echolocation signals of bats flying alone all showed similar characteristics. However, when flying in groups, each bat changed one characteristic of the echolocation signal, called the terminal frequency, in order to decrease the similarity between signals. They also produced longer and louder pulses, similar to how a person might raise their voice to be heard at a noisy party.
In this study, the authors tested bats only in groups of four, so it is still unknown whether the same strategy works when bats fly in much larger groups.