Think differently on the left

Why we hear differently with the left ear than with the right

Listening, understanding, processing - all at the same time. Our brains do amazing things when it comes to processing language quickly. Researchers were able to demonstrate for the first time in living people why the left hemisphere dominates

Whether in conversation, listening, reading or writing: language is a matter of the mind. We think in a language and we share our thoughts (mostly) in words. Language is therefore essential for interpersonal communication. In order to maintain the flow of the conversation, we try to guess the next words of our interlocutor before he has uttered them and at the same time process what has been said into new thoughts. And while we hear ourselves speaking the other way around, we automatically plan the next sounds before we articulate them.

A simple test shows that the left hemisphere is superior to the right hemisphere in these processes: If test subjects are played two different syllables in the left and right ears at the same time, most people state that they only heard what was in the right ear was said. The reason: language that is perceived through the right ear is processed in the left hemisphere.

It is interesting in this context that the so-called whistling language shows a different picture. In this, according to the result of the same test by Onur Güntürkün from the Ruhr University Bochum, the left hemisphere is not preferred. Because: Whistling language requires the perception and processing of pitch, melody, etc., for which areas of the right hemisphere are primarily responsible.

New insights into the microstructure of the brain region

"Scientists discovered a long time ago that a brain region that is important for language, called the planum temporale, is often larger on the left than on the right," explains Dr. Sebastian Ocklenburg from the Biopsychology Unit at the Ruhr University Bochum in a current press release. The nerve cells of the left planum temporale have a higher number of neuronal connections than those of the right hemisphere. "So far, however, it was unclear whether this asymmetrical microstructure is decisive for the superiority on the left in speech processing," adds Erhan Genç, also from the research team at the Ruhr University in Bochum and the Technical University of Dresden. Now, with the help of new measuring methods, they were able to obtain previously impossible insights into the microstructure of the brain region and thus bring the findings together with the speed of our language processing.

While the higher number of neural connections in the left brain region could previously only be determined in deceased people, thanks to a special form of magnetic resonance imaging, the density and spatial arrangement of nerve cell processes in the planum temporale of the left and right hemispheres can now be determined. The test on almost a hundred test subjects showed that test subjects with particularly fast language processing in the left hemisphere also had a particularly large number of nerve cell processes in the left planum temporale. “Because of this microstructure, the speech processing on the left is faster and the temporal precision with which what is heard is deciphered is probably also higher,” concludes Ocklenburg. “The higher interconnection density thus seems to be a decisive component for the linguistic superiority of our left brain hemisphere,” adds Genç.

It is interesting that people whose fiber connections are weakened in the left-sided brain region can literally stutter - at least several studies assume that. Stress and similar disruptive influences then cause the already disturbed system to collapse.