Researchers at Saarland University in Germany have disclosed that human ears move when we listen to sounds. This behavior, common in animals, helps them not only focus on specific noises but also help them to know the direction from which the sound is coming.

Though human ears are typically considered static, recent research by Andreas Schröer and his team has uncovered a surprising finding. Their study says that the movement of human ears, though subtle, is a leftover trait from our ancestors' ear-orienting system, a phenomenon they refer to as a “neural fossil.”

According to Schröer, the lead author of the study, it is believed that our ancestors lost the ability to move their ears around 25 million years ago, though the exact reason remains unclear. He explained, “However, we have been able to demonstrate that the neural circuits still seem to be present in some states. Our brain has retained some of the structures to move the ears, even though they are no longer useful.”

In previous studies, the research team found that these ear muscle movements occurred when humans focused on the direction of a sound. However, their latest discovery reveals that these movements also take place when a person is making an effort to hear a sound.

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For this experiment, the team worked with 20 adults who had no hearing impairments. Participants listened to an audiobook played by a speaker, while a podcast was also played from the same spot.

The research team conducted three different listening scenarios to examine the auriculomotor system in humans. The first scenario, the easiest, involved playing the podcast at a lower volume than the audiobook, with a noticeable difference in pitch between the voices.

The second scenario, the hardest, had two podcasts playing simultaneously, making the combined volume louder than the audiobook.

The final scenario featured one podcast played at the same pitch as the audiobook, while the other maintained the pitch from the previous scenario. Schröer explained that the experiment aimed to assess whether the auriculomotor system is sensitive to the effort involved in listening, likening it to trying to understand someone in a quiet restaurant versus a busy one.

The participants listened to each of the three scenarios twice, and the experiment was repeated with the speakers' positions switched. Schröer explained, "Almost nobody [in the study] could voluntarily move their ears, so our results are not related to a person’s ability to do this." Although the study was small and needs more testing with a larger group, the research team believes it offers useful insights into how our ears respond when we focus on listening.

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