A chirp is a signal that varies its frequency with time. Most biologically generated chirps start at one frequency and sweep down to another. Chirps that span many frequencies are called broadband and are those typically used by bats. Narrowband calls cover a narrower frequency range, focusing a lot of energy within a small range of frequencies. Echoes from broadband signals provide bats with the most detailed information about their targets.

A broadband set of chirps emitted over different frequency ranges.