It’s not just your pet: Human ears ‘perk up’ when hearing unexpected sounds

SAARBRUCKEN, Germany — Pet owners may enjoy a chuckle from seeing their furry friends “perk up” when hearing something interesting. It turns out cats and dogs aren’t the only ones to make these amusing little movements. Recent research finds human ears also perk up from an unexpected sound, just like other animals that move their ears.

About one in five people can control their muscles and wiggle their ears, researchers say. Although only a small portion can control this entertaining talent, a study by the University of Saarlandes in Germany says all humans can actually move their ears, but most of those actions are automatic.

A prehistoric ear wiggle?

If you watch animals at the zoo or pets in your home, you may see them perk up their ears in the direction of a new sound. Animals move their ears to focus their attention on the direction the sound comes from. Researchers say they wanted to know if humans do the same thing that animals and their distant ancestors did.

“It is very likely that humans still possess a rudimentary orientation system that tries to control the movement of the pinna (the visible outer part of the ear). Despite becoming vestigial about 25 million years ago, this system still exists as a ‘neural fossil’ within our brains,” says co-author and neuroscientist Danial Strauss in a press release.

To test this ancestral wiggling theory, the research team used a technique called electromyography (EMG) to record the electrical activity of the muscles around the ears. “The electrical activity of the ear muscles indicates the direction in which the subject is focusing their auditory attention,” notes Strauss.

Ear exercises

Research participants took part in two experiments. The first tests passive listening skills, where unexpected sounds play while the subject reads. The second experiment tests active listening skills, where participants need to focus on a story someone is reading while another researcher tells a “competing” story at the same time. In addition to EMG recordings, researchers also study high-speed videos of the participants while their ears react to these tasks.

Study authors say their results show the pinna-orienting system moving in the direction of the subject’s attention. So whether you realize it or not, your ears perk up and point towards the things that grab your attention.

It’s unclear why most humans no longer have the ability to consciously control their ears. But the study finds these unconscious movements are a remnant of our evolution.

Helping the hearing impaired

The authors comment on one possible application of these findings. They believe scientists will be able to create better hearing aids, since microphones can amplify the sounds the listener is focusing their attention on.

“These devices would be able to amplify the sounds that the wearer is trying to hear, while suppressing the noises that they are trying to ignore. The device would function in a way that reflects the user’s auditory intention,” Strauss explains.

The study is published in the journal eLife.

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