Bats produce a surprisingly wide range of sounds, from ultrasonic echolocation pulses far beyond human hearing to audible squeaks, chirps, screams, and even complex social calls directed at specific individuals. Most of what bats “say” happens above 20 kHz, making it invisible to our ears, but plenty of their vocalizations fall within the range people can detect.
Echolocation: The Sounds You Can’t Hear
The signature bat sound is echolocation, a rapid-fire series of ultrasonic pulses that bounce off objects and return as echoes the bat uses to navigate and hunt. These calls span a huge range, from about 11 kHz at the low end to 212 kHz at the extreme high end, depending on species. Most insect-eating bats call between 20 and 60 kHz. Since human hearing tops out around 15 to 20 kHz (and drops with age), the bulk of echolocation is completely silent to us.
Some species sweep through a wide band of frequencies in a single call. One European bat species, for example, produces calls that sweep from 135 kHz all the way down to 16 kHz, covering wavelengths from about 2.6 millimeters to 22 millimeters. That range lets the bat detect objects of very different sizes in a single pulse. A few bat species do produce echolocation calls with components below 20 kHz, which means portions of their sonar are technically audible to people standing nearby, though they sound like faint, rapid clicking.
Not all bats echolocate the same way. Most generate sound in the throat using specialized structures in the larynx, but fruit bats in the genus Rousettus take a different approach entirely: they echolocate using tongue clicks, producing very brief ultrasonic pulses similar to the sonar clicks of dolphins.
How Bats Physically Produce Sound
Bats have an unusual vocal setup. Their vocal folds end in extremely thin membranes, just 6 to 10 micrometers thick, that vibrate independently from the vocal folds themselves. These delicate membranes produce the high-frequency sounds used for echolocation and social calls, vibrating at frequencies between 10 and 70 kHz.
For lower-pitched, aggressive social calls, bats recruit a completely different structure: the ventricular folds, which sit just above the true vocal folds. These vibrate at 1 to 5 kHz, well within human hearing range. The mechanism is essentially the same one used by death metal vocalists to produce growling sounds. This dual system lets bats cover an enormous vocal range, from deep growls audible to people nearby all the way up to ultrasonic frequencies ten times higher than anything a human can detect.
Social Calls You Can Actually Hear
The squeaks, squawks, and chattering you might hear from a bat roost are social calls, not echolocation. These sounds serve purposes ranging from mother-pup bonding to territorial defense to mating displays. Many of these calls fall partly or entirely below 20 kHz, making them audible as high-pitched chirps, buzzes, or screeches.
When bats feel threatened or are in distress, they produce calls that are noisy, broadband, and very short, averaging less than 10 milliseconds each. Nearly half of these distress calls carry rapid amplitude fluctuations at about 1.7 kHz, creating a quality researchers describe as “roughness.” These fluctuations are more than ten times faster than the temporal patterns found in human screams. The result is a harsh, buzzy sound that’s quite distinct from their quieter social chatter.
Male bats of some species produce elaborate multi-syllable songs to attract females and defend their harems, sequences complex enough to qualify as true vocal performances rather than simple calls.
Bats Talk to Each Other, Not Just Around Each Other
Bat social communication is far more complex than random squeaking. Research on Egyptian fruit bats identified at least six distinct categories of social calls tied to specific situations: aggression over roosting spots, aggression during sleep disturbances, food-related disputes, mating conflicts, and two types of positive interactions. Squabbling over perch space dominated the recordings, accounting for 82 to 94 percent of categorized calls across different groups.
What makes this especially interesting is that bat vocal exchanges are pairwise. Individual bats take turns rather than one animal dominating the “conversation.” Their vocalizations are directed at specific individuals and vary depending on the social context, suggesting a level of communicative specificity that goes well beyond simple alarm calls or mating signals.
Baby Bats Babble Like Human Infants
Bat pups don’t emerge from the womb knowing how to vocalize properly. In at least one species, the sac-winged bat, pups go through a babbling phase strikingly similar to babbling in human babies. Researchers who recorded 20 pups over their three-month development found that bat babbling shares eight key features with human infant babbling, including reduplication (repeating the same syllable) and rhythmicity (producing sounds in a regular beat).
When pups are separated from their mothers, they produce “isolation calls” with individually distinctive acoustic signatures. These features are partly inherited, and mothers use them to locate and recognize their own pup among potentially thousands of calling babies in a crowded roost. Over time, pups refine their calls through practice, gradually shaping their vocalizations to match the adult repertoire of their colony. This vocal learning process parallels how human infants and songbirds develop their vocal abilities.
What You’d Hear Near a Bat
If you’re standing near a roosting colony, you’ll likely hear a chorus of high-pitched squeaks, clicks, and chattering, especially around dusk when bats are waking up and jostling for space. These sounds can range from soft chirps to surprisingly loud screeching during aggressive encounters. The low-frequency growls produced by ventricular folds (1 to 5 kHz) sound raspy and harsh, while social chirps tend to be higher and more tonal.
If a bat flies past you outdoors, you probably won’t hear anything at all. Its echolocation pulses are almost certainly above your hearing threshold. With a bat detector, a device that shifts ultrasonic frequencies down into the audible range, the same flyby becomes a rapid series of clicks or sweeping tones, depending on the species. Each bat family has a characteristic echolocation “voice” that trained listeners can identify on a detector the way a birder identifies a song.