Effects of acoustic interference on the echolocation behavior of bats

Echolocating bats analyze the echoes of self-generated ultrasound pulses to reconstruct three-dimensional images, enabling them to navigate in the dark. When they behave in proximity to conspecifics, bats are exposed to conspecific pulses with similar spectrotemporal characteristics of their echoes. Although the echolocation pulses emitted by bats have high intensity, the intensity of the echoes is decreased by attenuation and its scattering in the air. Intense sounds emitted by these bats or other sources can impair bat's ability to detect their echoes. Similarly, a stream of echoes from the environment and conspecific pulses creates an acoustically complex situation wherein bats differentiate and extract their target echoes from a mix of other sounds with similar acoustic characteristics. Here, we review previous studies that investigated how bats deal with acoustic interference in three conditions: auditory masking, clutter interference, and jamming. It was found that bats could improve the signal-to-noise ratio of echoes in the presence of noise, which resembles the Lombard effect observed in other animals. Emitted pulses are modified temporally and spectrally in response to conspecific sounds, implying that echolocating bats can actively separate acoustic characteristics to mitigate mutual interference among a group of conspecifics.