This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Bats can produce ultrasonic pulses with high frequencies between 20,000 and 120,000 hertz, which are inaudible to humans. The sound waves they produce travel forward, hitting nearby objects and bouncing back in the form of echoes.
This sophisticated echolocation system helps bats to effectively navigate their surroundings, avoiding obstacles and reaching their desired destinations. While bat echolocation is widely studied, how bats distinguish between their own sonar signals and those of other bats in their surroundings remains poorly understood. Researchers at the University of Toyama, Doshisha University, Nagoya University and Meiji University recently studied a bat species called Miniopterus fuliginosus to better understand how they can tell the echolocation signals produced by different bats apart.
Their paper, published in Proceedings of the Royal Society B, outlines a mechanism via which individual bats adjust their calls to produce a collective signal pattern and reduce echolocation interference. "We had been wondering how echolocating bats allocate their frequencies to avoid signal jamming during group flight," Kazuma Hase, first author of the paper, told Phys.org. "The study was inspired by a simple electronic RC circuit.
We hypothesized that if each bat integrates sound information from other bats over time with a leak—incorporating the asymmetric response where they are strongly influenced by lower frequencies but not higher ones—self-organized spectral adjustments could be achieved." Hase and his colleagues hypothesized that bats collectively separate the frequency of their respective calls by responding primarily to lower-frequency calls and less strongly to higher ones. To shed light on the possible mechanism underpinning their frequency control, they conducted a series of experiments involving 11 Miniopterus fuliginosus, commonly known as eastern bent-wing bats. The researchers attached a tiny wireless microphone to each bat's back and recorded its calls as it was flying alone.
Over the course of the experiment, they played sounds that might interfere with the animals' echolocation signals, varying the sounds' loudness and pitch, as well as the gaps between individual pulses. The team then analyzed the sonar signals emitted by the bats to determine whether they changed in response to the interference sounds. Hase and his colleagues developed a model representing the frequency adjustments made by individual bats, called the leaky-integrator model.
The leaky-integrator model combines incoming sound information over time, while gradually reducing the influence of older sounds. The researchers used this model to simulate a group of bats flying in two-dimensional space. "To capture the dynamics of these responses, we developed a leaky-integrator model—a mathematical model that integrates incoming sound information over time with a gradual decay," explained Hase.
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