Audio Illusion

Our linguistics professor showed us this "Audio Illusion" today in class and I thought you might have fun with it. Go to this you tube video and play it three times. The first time, listen to the video with your eyes closed and write down what sound you hear. Then, watch the video without the sound and write down what sound you see him making. Finally, watch with the sound and write what you think you hear.

Here's what's going on--it's called the McGurk Effect. You should have written down three different sounds, one for each time you watched the video. When we listen with our eyes closed, we hear ba, ba, ba. That's what the sound track actually says. When we watch without sound, we think he's saying ga, ga, ga, because the man we see is actually saying ga (we know by how his mouth looks). When we watch with sound, we think he's saying da, da, da, because we are combining the input we hear and see, trying to make sense of it. (b, d, and g are related sounds--d and g are the same except for where our tongue is (middle vs. back of the mouth), b is different because of where the tongue is (front) and because the lips are together.) So when we hear him saying ba, but it looks like he should be saying ga, our mind tries to find something in the middle, and we hear da. Cool, right?