Wiggling Your ears could be more a pub part of advertising than a survival skill, but humans always try to prick their ears when listening, researchers have found researchers.
The movement of the ear is crucial in many animals, in particular to help them focus their attention on particular noises and to determine which direction they come.
But while the human ear is much more static, the traces of the ear orientation system of our ancestors remain in what has been called a “neural fossil”.
“We think that our ancestors lost their ability to move their ears about 25 million years ago. Why exactly is difficult to say, “said Andreas Schröer, the principal of the University of Saarland in Germany.
“However, we have been able to demonstrate that neural circuits always seem to be present in a state, (that is to say) our brain has preserved certain structures to move the ears, even if they are apparently no longer useful . “
The team previously discovered that the movement of these muscles in humans is linked to Direction of sounds to which they pay attention. Now they have discovered that some of these muscles are activating when humans listen to a sound.
Writing in the newspaper Borders in neuroscienceThe team reported how they asked 20 adults without hearing problems listening to an audio book played through a speaker at the same time as a podcast was played in the same place.
The team created three different scenarios: in the “simplest” scenario, the podcast was quieter than the audio book, with a big difference in pitch between the voices. In the “hardest” scenario, two podcasts were played which, taken together, were stronger than the audio book, with one of the podcasts spoken to a field similar to the audio book.
“We were interested in discovering whether the Auriculomotor system in humans is sensitive to efficient listening. Remember to try to understand what someone says in an almost empty restaurant and try to understand someone in a very busy restaurant, “said Schröer.
Each participant has twice experienced the three different scenarios. This was then repeated with the speaker in a different position in the room. Each participant wore a set of electrodes, allowing researchers to record the electrical activity produced by the muscles involved in the reassembly of the ears.
After each test, the participants were invited to assess the efforts they spent listening to the audio book.
The results revealed that the listening effort perceived of the participants, and how often they focused on the audio book, increased as the scenario went from the simplest to the hardest.
The team found the activity in the upper auricular muscles, which lift their ear up and out, was larger in the most difficult listening conditions than during the easy and medium conditions. They also found that the posterior auricular muscles, which pulled their ears back, were more active when the sounds came from behind the participant than in front of them.
“Almost no one (in the study) had the ability to move voluntarily, so our results are not linked to a person’s ability to do so,” said Schröer, although he noted that D “Other research has shown that people could learn to move their ears.
Although the study is small and must be repeated in a larger and more diverse group, the team said that the results provided information.
“The movements of the ear that could be generated by the signals that we have recorded are so tiny – or even absent – that there is probably no noticeable advantage,” said Schröer. “We therefore think that this auriculumotor vestigian system” does its best “, but probably doesn’t get much.”