If I were to ask you “How do we process speech?”, you would probably answer “Thanks to our hearing, right?”. And you’d be... partially right.
Speech does indeed activate our temporal lobe, which is mostly devoted to our hearing abilities. It makes sense: we hear something and our brain analyze that sound to understand it. But that’s not all!
We also need our vision (occipital lobe). Yes, we rely quite strongly on the movements of our interlocutor’s lips/mouth.
The McGurck effect proves that: if I show you the video - without sound - of someone’s mouth pronouncing /ga/, but I add the sound of someone saying /ba/ over it, your brain will get confused. The visual input and sound input are in contradiction! Because if you look at your mouth in a mirror, you’ll see that /ga/ doesn’t make your lips move, but /ba/ does. So your brain hear /ba/, but doesn’t see the lips moving. Conclusion: it must have hear that incorrectly. It reaches for the second best option at its disposal: “it must have been /da/! Lips doesn’t move either for that one, and it’s close to /ba/!”
So if you show the video of /ga/ with the sound of /ba/, people will be absolutely certain they heard /da/.
If you do the opposite (video of /ba/ but sound of /ga/), then people will definitely hear /bga/. Because once again, the brain looks at the lips moving on the video and get confused - “lips aren’t supposed to move to say /ga/! I must have missed the /b/ at the beginning of the sound, then”. That’s how you get people to hear a consonant which was never there.
So, hearing and vision. They does help activating the parts dedicated to the language in our brain. But that’s still not it!
You’ll also need your motor cortex. Yes: to understand what’s being said to you, you need your motor skills. Confusing? I’ll explain.
First, those “language parts” of our brain I was talking about are right next to the motor cortex. And what is close interacts.
Then, you have what we call “mirror neurons”. They’re neurons that are activated in 2 situations: if you do something, and if you watch someone else do that thing. Basically, if you play soccer or if you watch a soccer match on TV, some of you neurons don’t care about the difference and activate both times.
Which means that when you listen to someone, your mirror neurons happily activate your pronunciation motor patterns. Those patterns help you understand what’s being said by ‘virtually trying to do the same’. Which is why it’s currently recommended for kindergarten teachers to wear transparent masks: kids are at a very important time in their process of learning the language and they need to see people’s mouth.
How is that important for you, you ask? Well, if we consider all this, I see 2 major points:
1/ don’t exagerate your pronunciation if you speak to someone who’s deaf/hard of hearing. It creates movements that are not natural, making it harder for their brain to find the same “pronunciation pattern” in their own “database”. Instead, simply speak naturally, maybe a bit slower if you see them struggling.
2/ but more importantly, for all the langblrs and everyone learning a language:
You’re having a hard time understanding your target language?
Try aiming for the mouth.
(by that I mean look at the mouth. But if you fall in love with a native and end up kissing them, it actually works quite well too)
