 |
| © Thomas Fuchs |
You are watching a foreign movie whose language you do not understand at all. Suppose, someone is speaking in French or Mandarin. Don’t you think that they are gurgling and making sounds in a row? It seems as if there are no pauses, commas or gaps between their words. The words are just coming to your ears like a huge long train.
However, when someone speaks in Bengali or English, you can clearly hear the different sounds. You can understand when one word ends and when a new one begins.
But in reality, when we speak, there is no pause between words! Scientists say that we pause more between the letters within words than between the words. In other words, there is no physical boundary between words. The fact that we hear different words is all a huge trick of our brain!
Recently, Edward Chang, a neuroscientist and neurosurgeon at the University of California, San Francisco, USA, and his team have solved this mystery. Their research has been published in the world-renowned journal Neuron and Nature. Let’s find out in simple terms how our brain makes this impossible possible.
Whenever we hear a word in a familiar language, there is a big drop in these high-gamma waves 100 milliseconds after the end of that word.
When we write in a notebook or type on a computer, we press the spacebar to leave a gap between two words. But when we speak, we can’t press the spacebar. So how does the brain understand?
Edward Chang and his team have studied the part of the human brain that is responsible for listening to speech. They have noticed that there is a type of electrical wave in our brain. It is called high-gamma wave. These waves fluctuate very quickly, about 70 to 150 times per second.
The study found a strange thing. Whenever we hear a word in a familiar language, exactly 100 milliseconds (one tenth of a second) after the word ends, there is a big drop in this high-gamma wave. Much like the dots on a heartbeat monitor fluctuate.
Scientist Chang says that this drop is the brain’s spacebar. Whenever this wave goes down, our brain understands that the previous word is over, and now a new word will begin. This signal only works in the brains of those who are proficient in that language.
Researchers conducted this experiment on English, Spanish and Mandarin speakers. It was found that when a native speaker listens to his own language, this high-gamma wave fluctuates in his brain at the right time. But if he is listened to another unknown language, his brain cannot give this signal. Then it seems to him that all the words have become one.
Interestingly, the brains of bilinguals or those who know two languages well have this high-gamma web of oscillations equally in both languages. On the other hand, if someone is learning a new language, the more proficient they are, the stronger this signal in their brain will be. In other words, learning a language actually means teaching the brain to recognize this secret signal.
Until now, scientists believed that sound is processed in one part of our brain, it goes to another part to become sound, and then it goes to another part to create its meaning.
While Evelina Fedorenko, a neuroscientist at the Massachusetts Institute of Technology in the United States, praised this research, she raised an important question. She says, can the brain make this division because it understands the meaning of the word? Or has it memorized the pattern or type of the word by listening to it repeatedly?
For example, when we hear unclear words in a movie, we do not understand them. But when we turn on the subtitles, those unclear words suddenly become clear. That is, if we know the meaning, it is easier to hear the word. Evelina believes that there is a complex relationship between hearing words and understanding grammar.
Until now, scientists used to think that our brains worked in stages, like a factory. In one place, sound is processed, in another place it becomes sound, and then in another place its meaning is created. But Edward Chang’s research has completely changed that idea.
Chang said, “This new result has overturned all the old ideas. In fact, everything is happening in the same place. When our brain is processing the sound of a word, it is also recognizing it as a word at the same moment.”
That means that our brain is making millions of calculations every moment without us knowing it. When you are chatting with a friend, the supercomputer inside your head is creating word boundaries with high-gamma waves every second, so that you can understand the gist of the story.
Source: Scientific American
