Ears are a peculiarly individual piece of anatomy. Those little fleshy seashells, whether they stick out or hang low, can be instantly recognizable in family portraits. And they aren’t just for show.

Researchers have discovered that filling in an external part of the ear with a small piece of silicone drastically changes people’s ability to tell whether a sound came from above or below. But given time, the scientists show in a paper published Monday in the Journal of Neuroscience, the brain adjusts to the new shape, regaining the ability to pinpoint sounds with almost the same accuracy as before.

Scientists already knew that our ability to tell where a sound is coming from arises in part from sound waves arriving at our ears at slightly different times. If a missing cellphone rings from the couch cushions to your right, the sound reaches your right ear first and your left ear slightly later. Then, your brain tells you where to look.

But working out whether a sound is emanating from high up on a bookshelf or under the coffee table is not dependent on when the sound reaches your ears. Instead, said Régis Trapeau, a neuroscientist at the University of Montreal and author of the new paper, the determination involves the way the sound waves bounce off outer parts of your ear.