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New Study Reveals How Ear Muscles Help Us Listen Better

In an unexpected finding, researchers discovered that the auricular muscles, which previously helped our ancestors adjust their ears to increase hearing, are still active when we strain to listen in noisy situations. These muscles, which are now vestigial and only utilised for twitching our ears, may provide useful information about how we focus on specific sounds.

The auricular muscles, which attach the outer ear (auricle) to the skull and scalp, used to play an important role in increasing hearing quality by modifying the shape of the pinna, the ear shell. Over millions of years, humans lost the ability to properly use these muscles, but they are still there in our anatomy. Andreas Schröer of Saarland University, the lead author of the study published in Frontiers in Neuroscience, explains that certain muscles, particularly the superior auricular muscle, become more active when we attempt to listen to competing noises.

"These muscles, particularly the superior auricular muscle, exhibit increased activity during effortful listening tasks," Schröer reports. "This suggests that these muscles are engaged not merely as a reflex but potentially as part of an attentional effort mechanism, especially in challenging auditory environments."

Researchers ran an experiment with 20 people who did not have hearing issues to better understand how these muscles respond to various listening settings. They plugged electrodes into the participants' auricular muscles and played an audiobook and distracting podcasts from speakers placed in front or behind them. The subjects completed 12 five-minute trials with different levels of difficulty.

In the simplest mode, the podcast was quieter than the audiobook, which made it easier to concentrate. In the more challenging modes, the podcasts were louder and more similar to the audiobook, making it difficult to concentrate. Participants rated their effort and how frequently they lost track of the audiobook. They also addressed questions regarding the audiobook's content. 

The study discovered that the posterior auricular muscles responded to changes in direction, whereas the superior auricular muscles responded to the difficulty level of the job. As the difficulty grew, participants reported greater effort and more frequent loss of focus. Their accuracy in answering audiobook-related questions also declined.

The activity of the superior auricular muscles was related to the difficulty of the test, implying that these muscles could provide an objective measure of listening effort. However, it is uncertain if this muscle action improves people's hearing.

"The ear movements that could be generated by the signals we have recorded are so minuscule that there is probably no perceivable benefit," according to Schröer. "However, the auricle itself aids in our ability to localise sounds. So, after being vestigial for 25 million years, our auriculomotor system presumably gives it its all but doesn't accomplish much."

The researchers agree that additional research is required to confirm these findings and investigate practical applications. They believe that larger, more diverse participant groups and more realistic circumstances are required for future studies. Future research could focus on the impact of muscle strain and microscopic ear movements on sound transmission, particularly in those with hearing impairments.

This study emphasises the intriguing significance of auricular muscles in our ability to concentrate on certain sounds in noisy surroundings. While these muscles may not considerably improve our hearing, their activity could be used as an objective indicator of listening effort. Further research could lead to a greater understanding and potential uses for enhancing hearing aids and assisting those with hearing loss.


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