Researchers have found that the muscles move to guide their ears into the sound source in a vestigial reaction.
Shaking the ears can be more than one survival skillbut humans still try pull the ears when they are listening carefullydiscovered the investigators.
According to the ears movement is crucial in many animals, especially for help focus your attention on specific noise and realize what direction they come.
However, although the Human ear is much more staticthe traces of the ear guidance system of our ancestors remain in what a “neural fossil“.
“It is thought that our ancestors have lost their ability to move their ears about 25 million years ago. It’s hard to say why, exactly, ”he said Andreas Schröerthe main author of the research of the University of Saarland, Germany.
“However, we can demonstrate that neural circuits still appear to be present in some state, that is, the Our brain retained some of the structures to move the earsalthough apparently no longer useful. ”
The team previously discovered that the movement of these muscles in humans is related to the direction of the sounds to which they are paying attention. Now they have found that some of these muscles are activated when humans carefully hear a sound.
In the magazine, the team reported how they asked the 20 adults without hearing problems that heard audiobook reproduced by a loudspeaker at the same time as a podcast It was reproduced in the same place.
A Team created three different scenarios: In the “easiest” scenario, the podcast It was quieter than audiobook, with a big difference in tone between the voices.
In the “hardest” scenario, two podcasts which, together, were higher than audiobook, being one of the podcasts spoken in a tone similar to that of audiobook.
“We were interested in finding out if the auriculomotor system of humans is sensitive to hearing with effort. Think about trying to understand what someone is saying in a almost empty restaurant and trying to understand someone in a very busy restaurant, ”said Schröer.
Each participant experienced the three different scenarios twice. Then the experience was repeated with the speaker in a different position in the room. Each participant used a set of electrodes, allowing researchers to record the electrical activity produced by the muscles involved in the movement of the ears.
After each rehearsal, participants were asked to to classify the effort they spent on hearing the audiobook.
The results revealed that the perception of the participants’ auditory effort e the frequency with which they lost concentration in audiobook They increased as the scenario became easier for the hardest.
The team found that the activity, which raise the ear up and out, was higher during the more difficult hearing conditions than during easy and medium conditions.
They also found that the posterior ear muscles, which pulled the ear backwards, were more active when the sounds came from behind the participant than in front of him.
“Almost no one had the ability to voluntarily move their ears, so our results are not related to a person’s ability to do so,” says Schröer, although he said that Other studies have shown that people can learn to move their ears.
Although the study is small and needs to be repeated in a larger and more diverse group, the team states that Results provided knowledge.
“The movements of the ears that could be generated by the signs we record are so tiny – or even nonexistent – that there is probably no noticeable benefit,” said Schröer. “That’s why we think this Auticulmotor System Testigial is ‘trying your best’but probably can’t do much. ”
Teresa Oliveira Campos, Zap //
