Echolocating is the ability to produce a sound and to listen to the reflection of that sound to get an idea about where you and objects around you are in the world. Most people know that bats are capable of this. But did you know that some humans are capable of this too, and that bats have some more vocal tricks up their sleeve?

How do bats echolocate?

Bats use a variety of intriguing ways to make echolocation sounds. Some bats can emit really high-pitched sounds with their vocal organs (called the larynx). Other bats create these high-pitched sounds with their nose. Some bats find more creative ways to echolocate. There are bats that click their tongue, and listen to the echoes of these tongue-clicks 1. Recently, researchers found out that some bats even clap their wings together as a form of echolocation 2! 

The intriguing case of human echolocation

An illustration of how echolocation works. The echolocator makes a sound.  The emitted sound waves are reflected back onto the echolocator from objects in their environment and they can then infer information about these objects from these reflected sound waves. 

These last two forms of echolocation, tongue-clicking and tapping objects together, have been used by humans as well. Blind individuals have been known to teach themselves these forms of echolocation, either by clicking their tongue or tapping a cane on the floor. This allows them to successfully navigate their way through our world and avoid obstacles.

Research shows that when listening back to these human echolocation sounds, different brain areas are active in humans who have taught themselves echolocation than in blind or sighted humans who have not, showing that learning to echolocate partially changes your brain 3! Particularly, brain areas involved in vision, spatial orientation, and object movement are involved in listening tro echolocation sounds in skilled echolocators. 

Bats can learn to produce new sounds, just like humans

Now that we have learned the surprising fact that both bats and humans can echolocate, are there any other vocal abilities we have in common? As humans, we have the unique ability of communicating with one another via spoken language. No other animal can communicate with each other quite like we do. However, we do share certain skills involved in language learning and production with a select group of animals.

The echolocating and vocal learning pale spear-nosed bat.

One such skill, the ability to learn to produce novel sounds (called vocal learning), can be found in some echolocating bats. For example, young pale spear-nosed bats, just like human babies, learn to imitate the sounds their parents make 4. They can even learn to change their calls based on what kind of sounds you play to them over speakers. This ability to learn to produce new sounds is something that cats, dogs, or even our non-human primate relatives cannot do. 

How is echolocating and learning new sounds supported by our brains?

Some researchers argue that echolocating and vocal learning go hand in hand: both skills require finely-tuned listening abilities and a keen ability to use what you hear to decide what sounds you are going to produce next. How are both of these skills represented in our brains? Previous research shows that partially overlapping brain areas are involved in both abilities in the pale spear-nosed bat 5.

At the Max Planck Institute for Psycholinguistics, researchers from human neuroscience and bat molecular biology have come together to study how the brain of the pale-spear nosed bat is organized, and which brain regions and pathways might support echolocating and which might support vocal learning. To study this,  they are using magnetic resonance imaging (MRI) to see how brain regions are connected to each other and molecular biology techniques to see in which brain areas certain genes related to vocal learning are active. They hope this will give us insight into especially how vocal learning works in the brains of mammals (like us!), something which is currently not very well known.

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Sources

  1. Yovel, Y., Geva-Sagiv, M., & Ulanovsky, N. (2011). Click-based echolocation in bats: Not so primitive after all. Journal of Comparative Physiology A, 197(5), 515–530. https://doi.org/10.1007/s00359-011-0639-4
  2. Boonman, A., Bumrungsri, S., & Yovel, Y. (2014). Nonecholocating Fruit Bats Produce Biosonar Clicks with Their Wings. Current Biology, 24(24), 2962–2967. https://doi.org/10.1016/j.cub.2014.10.077
  3. Fiehler, K., Schütz, I., Meller, T., & Thaler, L. (2015). Neural Correlates of Human Echolocation of Path Direction During Walking. Multisensory Research, 28(1–2), 195–226. https://doi.org/10.1163/22134808-00002491
  4. Vernes, S. C., & Wilkinson, G. S. (2019). Behaviour, biology, and evolution of vocal learning in bats. Phil. Trans. R. Soc. B, 1–31. https://doi.org/10.1098/not
  5. Fenzl, T., & Schuller, G. (2002). Periaqueductal gray and the region of the paralemniscal area have different functions in the control of vocalization in the neotropical bat, Phyllostomus discolor. European Journal of Neuroscience, 16(10), 1974–1986. https://doi.org/10.1046/j.1460-9568.2002.02261.x