Despite having no ears, snakes have surprisingly sensitive hearing: study

The king Cobra named 'Sir Vaas' and later renamed 'Houdini' is back in his terrarium at Skansen Zoo after being on the run for a week, in Stockholm, Sweden, Monday Oct. 31, 2022. (Tim Aro/TT News Agency via AP)

They may not have ears, but a new study suggests snakes might be able to hear better than you think.

Researchers from Australia's Queensland University looked into how various species of snakes responded to sound. Their study, published in the journal PLOS ONE last week, involved 19 snakes from five genetic subfamilies.

“Because snakes don’t have external ears, people typically think they’re deaf and can only feel vibrations through the ground and into their bodies,” lead author Christina Zdenek said in a news release. “But our research – the first of its kind using non-anesthetised, freely moving snakes – found they do react to soundwaves travelling through the air, and possibly human voices.”

The researchers conducted experiments with the snakes in a soundproof room and observed their body movement as well as any hissing, tongue-flicking and any head or jaw movements in responses to three different sounds.

Different types of frequencies were also tested, including a low frequency sound in the range of 1 to 150 Hz that would make the ground vibrate, a mid-frequency sound in the range of 150 to 300 Hz, and a high frequency sound between 300 and 450 Hz.

The reactions to the sounds varied depending on species. Woma pythons were the only snakes that increases their movement in respond to sound and actually tended to move toward it.

"Woma pythons are large nocturnal snakes with fewer predators than smaller species and probably don’t need to be as cautious, so they tended to approach sound,” Zdenek said.

However, death adders, taipans and brown snakes were more likely to move away from sound, suggesting sound may be one of the ways they avoid predators. Taipans, in particular, showed signs of defensiveness and caution behaviour.

"Taipans may have to worry about raptor predators and they also actively pursue their prey, so their senses seem to be much more sensitive,” Zdenek added.

The study also found that it's likely that snakes could hear humans talk. The mid-frequency sounds used in the experiment were within the frequency of the human voice. The death adders moved away from the speakers when the researchers played the lower and mid-frequency sounds while the taipans only displayed their defensive behaviour in response to the mid-frequency.

“We know very little about how most snake species navigate situations and landscapes around the world. But our study shows that sound may be an important part of their sensory repertoire," said Zdenek “Snakes are very vulnerable, timid creatures that hide most of the time, and we still have so much to learn about them.”