<P> Echolocation calls have been measured at intensities anywhere between 60 and 140 decibels . Certain microbat species can modify their call intensity mid-call, lowering the intensity as they approach objects that reflect sound strongly . This prevents the returning echo from deafening the bat . High - intensity calls such as those from aerial - hawking bats (133 dB) are adaptive to hunting in open skies . Their high intensity calls are necessary to even have moderate detection of surroundings because air has a high absorption of ultrasound and because insects' size only provide a small target for sound reflection . Additionally, the so - called "whispering bats" have adapted low - amplitude echolocation so that their prey, moths, which are able to hear echolocation calls, are less able to detect and avoid an oncoming bat . </P> <P> Calls can be composed of one frequency or multiple frequencies comprising a harmonic series . In the latter case, the call is usually dominated by a certain harmonic ("dominant" frequencies are those present at higher intensities than other harmonics present in the call). </P> <P> A single echolocation call (a call being a single continuous trace on a sound spectrogram, and a series of calls comprising a sequence or pass) can last anywhere from 0.2 to 100 milliseconds in duration, depending on the stage of prey - catching behavior that the bat is engaged in . For example, the duration of a call usually decreases when the bat is in the final stages of prey capture--this enables the bat to call more rapidly without overlap of call and echo . Reducing duration comes at the cost of having less total sound available for reflecting off objects and being heard by the bat . </P> <P> The time interval between subsequent echolocation calls (or pulses) determines two aspects of a bat's perception . First, it establishes how quickly the bat's auditory scene information is updated . For example, bats increase the repetition rate of their calls (that is, decrease the pulse interval) as they home in on a target . This allows the bat to get new information regarding the target's location at a faster rate when it needs it most . Secondly, the pulse interval determines the maximum range that bats can detect objects . This is because bats can only keep track of the echoes from one call at a time; as soon as they make another call they stop listening for echoes from the previously made call . For example, a pulse interval of 100 ms (typical of a bat searching for insects) allows sound to travel in air roughly 34 meters so a bat can only detect objects as far away as 17 meters (the sound has to travel out and back). With a pulse interval of 5 ms (typical of a bat in the final moments of a capture attempt), the bat can only detect objects up to 85 cm away . Therefore, the bat constantly has to make a choice between getting new information updated quickly and detecting objects far away . </P>

Dolphins also use echolocation or the use of sound reflections to locate objects