Bats navigate dense, dark environments and pinpoint prey by listening to subtle changes in sound echoes. New research shows these flying mammals rely on a concept called "acoustic flow" to process thousands of overlapping echoes in real time. This allows them to fly at full speed without crashing into obstacles.[bristol+2]
How Bats "See" with Sound
Bats use a specialized system called echolocation, or biosonar, to understand their surroundings. They emit high-frequency sound waves, known as ultrasound, which are mostly between 14,000 and over 100,000 Hertz. Humans cannot hear these sounds, as typical human hearing ranges from 20 to 20,000 Hertz.These sound waves travel outward and bounce off objects in the environment. The echoes then return to the bats' finely tuned ears.[nps+5]
By interpreting these returning echoes, bats gather a wealth of information. They can determine an object's distance, size, shape, density, and even its texture. They also understand the direction an object is moving.Bats create these ultrasonic calls using their larynx and typically release the sound through their open mouth or sometimes their nose.Different bat species have unique call patterns and adjust their sounds for various purposes, such as searching for food, feeding, or communicating with other bats.[en+6]
When a bat detects an insect it wants to eat, it changes its call pattern. It produces a rapid series of calls, often called a "feeding buzz." This intense burst of sound, sometimes reaching up to 200 clicks per second, helps the bat pinpoint the exact location of its prey before it swoops in for the catch.[nps+2]
Acoustic Flow Guides Flight
Scientists have long wondered how bats manage to navigate extremely complex environments, like thick forests or dense hedges, without hitting obstacles. A new study, led by the University of Bristol and published in January 2026, has shed light on this mystery.Researchers found that bats do not try to track every single echo from every object. Instead, they interpret the overall pattern of how echoes change as they move forward.This pattern is known as "acoustic flow velocity."[bristol+5]
"Bats have a remarkable sensory system," said Dr. Athia Haron, the study's lead author from Bristol's School of Civil, Aerospace and Design Engineering. "How they manage to navigate complex habitats filled with many different obstacles and pinpoint prey with such precision has only now begun to be understood."Haron explained that a single bat call returns echoes from many objects at different distances and directions. Trying to analyze each individual echo would be too difficult.[bristol+3]
Professor Marc Holderied, from Bristol's School of Biological Sciences, compared acoustic flow to how objects appear to rush past your eyes faster when you speed up on a bicycle. "As bats fly and emit their calls, echoes return at slightly different rates depending on how close objects are and how fast the bat is flying," Holderied explained. "This creates a kind of sound flow."By sensing changes in this sound flow, bats can map their surroundings and accurately judge their speed.[bristol+3]
To test this theory, the research team built a unique "Bat Accelerator Machine." This machine featured an eight-meter flight corridor lined with revolving hedge-like panels. These panels held 8,000 artificial leaves, designed to mimic the natural echoes of a real hedge.Researchers recorded 181 flight paths of pipistrelle bats over three nights.They found that when the acoustic flow speed was increased by moving the reflectors against the bats' flight direction, the bats flew up to 28% slower. Conversely, when reflectors moved in the bats' flight direction, the bats accelerated.These adjustments show that bats are highly sensitive to changes in the Doppler shift, which is a key part of acoustic flow, and use it to control their speed and navigate.[mrcvs+4]
New Insights into Hunting
Another recent study, published in January 2026 by the Smithsonian Tropical Research Institute, explored how some bats hunt silent, motionless prey.Bat ecologist Inga Geipel and her team used a robot to mimic the echolocation abilities of common big-eared bats.These bats are known to use leaves as "acoustic mirrors" to find insects that are otherwise hard to detect.[smithsonianmag+4]
Geipel explained that just as light can bounce off a mirror at an angle to reveal an object, bats use leaves in a similar way. "You don't get the light reflected back to you," she said, describing shining a light at a steep angle. "But it could bounce off another object—like a dragonfly resting on a leaf—which reflects the light back into your face. That's what the bats do." Therobot bat demonstrated that as a bat flies and makes its rapid clicking sounds, the angles of nearby leaves change relative to the bat. This allows the bat to distinguish the weak echo from an empty leaf from the stronger echo of a leaf holding prey.[smithsonianmag]
The Bat's Inner Ear
The ability of bats to process these complex sound signals is rooted in their unique biology. A study published in January 2022 revealed that different groups of echolocating bats have distinct inner ear structures. Theinner ear contains a snail-shaped tube called the cochlea, which is lined with sensory hair cells. These cells vibrate in response to sound waves and convert them into neural signals that travel to the brain.[biologicalsciences+1]
Researchers found that "Yang" bats, which make up most bat species and use more complex, modulated frequencies for echolocation, have an open canal connecting nerve cells to the auditory nerve. This differs from "Yin" bats and most other mammals, which have a thick canal wall with tiny openings. Themore open structure in Yang bats allows for greater variation in neurons, suggesting different ways of processing echolocation signals and contributing to their diverse foraging methods.[igb+3]
Future Implications
These discoveries about bat navigation could have significant implications for technology. The principle of "acoustic flow" could inspire new methods for navigation in drone technology and autonomous vehicles. This could allow such machines to navigate complex environments more efficiently, especially where cameras, GPS, or light might fail. Dr.Shane Windsor, a co-author of the Bristol study, noted that the experiment showed bats rely on acoustic flow for speed control, providing evidence for its use in navigation.[bristol+1]
