An FM (frequency-modulated) chirp is a sound pulse that sweeps through a range of frequencies — in most bat species, from around 80 kHz at the start down to 20 kHz at the end. The sweep takes only a few milliseconds. Using a wide frequency band rather than a single tone provides much better range resolution: shorter wavelengths (high frequencies) resolve fine details, while the broad bandwidth allows pulse-compression techniques in the bat's auditory cortex analogous to radar chirp processing. This gives bats sub-millimetre target discrimination at short ranges.

Dolphins (and toothed whales) produce clicks rather than continuous FM sweeps, generated in a specialised nasal tissue called the phonic lips and focused into a beam by a fatty organ called the melon. Clicks span a broad frequency range (1–150 kHz) and travel at approximately 1500 m/s through water — about 4.4 times the speed in air — enabling dolphins to detect fish at ranges of 100 m or more and discriminate objects differing by only a few millimetres. The same physics (d = c·t/2) applies, but with a much higher propagation speed.

Most bat echolocation calls are ultrasonic — above 20 kHz, the upper limit of human hearing. A few species (e.g. the Pteronotus bat) produce calls partly within the human audible range, but the characteristic FM sweeps from 80 kHz down to 20 kHz used by common insectivorous bats are almost entirely inaudible. Researchers use bat detectors that heterodyne or time-expand the signals into the audible range to study bat behaviour in the field.

The Italian naturalist Lazzaro Spallanzani suspected in 1794 that bats navigated by hearing rather than sight after blinding them and observing they still avoided obstacles. However, the ultrasonic nature of their calls was not confirmed until 1938, when the Harvard undergraduate Donald Griffin used a newly invented ultrasonic microphone (built by George Pierce) to detect the high-frequency pulses. Griffin coined the term "echolocation" in 1944 and spent decades establishing it as a field of scientific study.

Echolocation is closely related to the Doppler effect: bats hunting moving prey detect the frequency shift in the returning echo and can calculate the prey's velocity — some species (horseshoe bats) specialise in Doppler-shift hunting. The simulation's related links include Doppler Effect, Sound Waves, and Beat Frequency, all of which describe properties of the same acoustic waves used in echolocation. Sonar, LIDAR, and radar are engineering analogues using sound, light, and radio waves respectively.

SONAR (Sound Navigation And Ranging) was developed for submarine detection in World War I and uses the same time-of-flight principle (d = c·t/2) with sound in water. Medical ultrasound imaging fires pulses of 2–15 MHz through tissue and reconstructs images from the echoes — modern phased-array transducers can produce real-time video at 30 frames per second. Ultrasonic parking sensors in cars, fish-finders, flow meters in pipelines, and non-destructive testing of materials all rely on the same biologically-inspired acoustic ranging principle.

Active research areas include understanding how bat brains solve the "cocktail party" problem — discriminating their own echoes from those of hundreds of other bats simultaneously — and how bats adapt their calls in real time (pulse interval compression as they approach prey, known as a "feeding buzz"). Neuroscientists study the bat auditory cortex as a model for time-delay neural computation. Engineers are applying machine-learning models trained on bat sonar data to improve autonomous vehicle LiDAR processing and to develop bio-inspired sonar for small robotics operating in complex environments.