Sound plays an important role for many animals, helping them navigate and hunt. Echolocation is the ability of animals like bats and dolphins to locate objects by emitting sound waves and interpreting the returning echoes. But detecting meaningful information in a noisy environment poses a major challenge for them. Bats operate by identifying weak prey echoes among complex background sounds generated by surrounding objects and their own movement during flight. To overcome this issue, these bats have evolved a highly sophisticated echo detection system that uses ultrasonic voices to perceive their surroundings with remarkable precision.
Investigating this, a group of scientists led by Doctoral Student Soshi Yoshida, Graduate School of Life and Medical Sciences, Doshisha University (currently a JSPS Overseas Research Fellow at the American Museum of Natural History), together with Professor Kohta Kobayasi and Professor Shizuko Hiryu has uncovered a unique strategy used by greater Japanese horseshoe bats (Rhinolophus nippon) to improve prey detection under noisy conditions. The study published online in the journal Communications Biology on May 19, 2026, reveals that bats do not simply process sounds passively, but actively manipulate the sounds from the surrounding environment to enhance important signals.
Horseshoe bats follow a phenomenon called Doppler shift compensation (DSC). Doppler shift is the change in the frequency or pitch of a sound or light wave caused by the movement of the source or the observer. When a bat flies, the frequency of returning echoes changes due to the Doppler effect caused by its motion relative to surrounding objects. To maintain these echoes within the most sensitive range of hearing, bats continuously adjust the frequency of their outgoing echolocation calls. So far, DSC has been primarily understood as a mechanism for stabilizing auditory perception. However, researchers suspected that this behavior may have another important function.
"I have always been fascinated by bats' ultrasonic sensing abilities and their use of physical phenomena such as the Doppler effect," says Yoshida. "This inspired me to explore whether bats use frequency control more strategically than previously understood."
To explore this possibility, the researchers performed a series of experiments using 11 wild-caught greater Japanese horseshoe bats. Using phantom echo playbacks (artificially created echo sounds) and by changing the frequency and intensity of the echo sounds, they determined which sounds triggered a DSC behavior in bats. The team also used onboard microphones to record real echoes received by bats during free flight and prey capture attempts. By using tethered moths, the team studied the echoes created by insect wingbeats. Additional sound playback experiments helped them understand how bats reacted when certain sound ranges were blocked or hidden.
The experiments revealed that bats control their echolocation calls to keep the highest-frequency echoes at a constant reference frequency (fref). Furthermore, this control creates a "silent frequency zone" above fref that is free from clutter echoes. This helps them detect important signals more clearly, including the faint echoes produced by the wingbeats of the flying insects.
The findings also demonstrated that this silent frequency region plays a critical role in hunting success. Introducing a narrow-band noise artificially into the clutter-free frequency region led to a decrease in the bat's hunting success. In contrast, noise produced outside this frequency range had minimal effects on the same. This confirms that the silent spectral window is not merely a side effect of echolocation but an adaptive sensory strategy that enables bats to hunt more effectively in noisy environments.
Highlighting the significance of the study, Hiryu says, "I am truly delighted that this study has finally clarified the fundamental role of DSC, a question that has fascinated me since my PhD student days. Our findings show that bats actively shape the acoustic environment to enhance perception, manipulating the physical properties of echoes rather than relying solely on neural processing. This study reminded us once again of how remarkably intelligent bats are in their use of the acoustic world."
Overall, the study provides insights on how animals solve sensory challenges under natural conditions, especially in cluttered places such as forests. These findings may also have broader implications for wireless technologies, particularly those that rely on waves such as ultrasound, sonar, radar, and imaging systems. The strategic discovery in bats may inspire new approaches in which these sensing systems actively shape signal environments to extract important information even in noisy and complex conditions.
About Soshi Yoshida, JSPS Overseas Research Fellow
Dr. Soshi Yoshida received his Doctor of Engineering degree from the Graduate School of Life and Medical Sciences at Doshisha University, Japan, in March 2026 and is currently affiliated with the American Museum of Natural History as a JSPS Overseas Research Fellow. His research focuses on bat echolocation, bioacoustics, sensory ecology, and neuroethology, especially how bats use Doppler-shifted sounds for navigation and prey detection. In recognition of his contributions, he received the prestigious JSPS Overseas Research Fellowship, awarded by the Japan Society for the Promotion of Science.
About Professor Shizuko Hiryu from Doshisha University, Japan
Shizuko Hiryu is a Professor in the Faculty of Life and Medical Sciences, Department of Biomedical Information at Doshisha University. She joined IBM Japan, Ltd. in 1999 and obtained a Ph.D. in Engineering from Doshisha University in 2006. Her research interests include ultrasonic engineering, bat bioacoustics, and sensing. She has published extensively on these topics in scientific journals, including several papers on echolocation and acoustic simulations in bats. From 2014 to 2018, she served as a JST PRESTO researcher. She is a member of several academic societies and committees and has received numerous awards for her work on echolocation and bioacoustics in bats, such as the MEXT Young Scientists' Prize and the JSPS Award.
Researcher profile
https://researchmap.jp/Shizuko_Hiryu/?lang=en
Lab page
https://www1.doshisha.ac.jp/~bioinfo/index.html
Funding information
This work was supported by JSPS KAKENHI Grant Number 21H05295 (H.S.), JSPS KAKENHI Grant Number 24H00723 (H.S.), JSPS KAKENHI Grant Number 25H00745 (H.S.), JSPS KAKENHI Grant Number 24KJ2144 (S.Y.).
