Neuroscientists at the Swiss Federal Institute of Technology Lausanne (EPFL) have found that positively colored human voices, such as laughter, cause more brain activity when heard from the left side. The research was published in the journal Frontiers in Neuroscience.
The scientists analyzed brain images of 13 adults. When study participants listened to cheery human voices coming from three different directions (left, middle, or right), both sides of their auditory cortex were activated. But recordings sent to the left ear elicited a much stronger brain response. These results were observed only for pleasant sounds. Neutral or negative, such as meaningless vowels or frightened screams, did not include such associations with the left.
Scientists have noted that increased sensitivity to certain sounds from certain directions makes evolutionary sense. Mankind’s survival over the last millennium undoubtedly depended on its extreme suspicion of the voices behind it. However, it is not so easy to explain the sensitivity to the sounds on the left.
It is known that some brain functions are related to the left hemisphere rather than the right and vice versa, but in this particular case this does not explain the results. However, previous research has shown that if the sound is directed to the left ear, it may be easier for a person to recognize the emotional tone in their voice. Further research will help to understand the reasons for this feature of the brain.