Ancient ear-wiggling muscles kick on when people strain to hear. That auricular activity, described January 30 in Frontiers in Neuroscience, probably doesn’t do much, if anything. But these small muscles are at least present, and more active than anyone knew.
You’ve probably seen a cat or dog swing their ears toward a sound, like satellite dishes orienting to a signal. We can’t move our relatively rigid human ears this dramatically. And yet, humans still possess ear-moving muscles, as those of us who can wiggle our ears on demand know.
Neuroscientist Andreas Schröer and colleagues asked 20 people with normal hearing to listen to a recorded voice while distracting podcasts played in the background. All the while, electrodes around the ears recorded muscle activity. An ear muscle called the superior auricular muscle, which sits just above the ear and lifts it up, fired up when the listening conditions were difficult, the researchers found.
Millions of years ago, these muscles may have helped human ancestors collect sounds. Today, it’s doubtful that this tiny wisp of muscle activity helps a person hear better, though scientists haven’t tested that. “It does its best, but it probably doesn’t work,” says Schröer, of Saarland University in Saarbrücken, Germany.
These vestigial muscles may not help us hear, but their activity could provide a measurement of a person’s hearing efforts. That information may be useful to hearing aid technology, telling the device to change its behavior when a person is struggling, for instance.
Schröer says the wide variety of ears — and wiggling abilities — is a challenge for research on ear muscles. “There’s actually quite a bit of variability in the size of your auricular muscles, which is sometimes also a bit difficult for us when we want to record [their activity].”
An ear wiggler himself, Schröer has collected stories of remarkable ear abilities, such as people who feel their ears moving toward a sound and people who use their ear movements in daily life. “They just wiggle their ears a little bit, and then their glasses are back on their nose where they belong,” he says.
This ear wiggling research is comforting to some people with exceptional ear control, Schröer says. “They really appreciate it because they always thought they were kind of strange.”