I read an article about a week ago from The Guardian about internal monologue. The article explained how internal monologue (the voice you hear when you read something), is accompanied by tiny movements of your vocal cords.
I have been thinking a lot along these lines as to how this motion could be captured and used. I think with the proper setup, this movement could be an indicator of what someone is thinking. (that’s right, mind reading)
However, since your vocal cord movements don’t make up all of your speech, this technique would probably be limited to discovering tone and inflection. For example, when asked a yes or no question that people know the answer to, many will immediately respond (mentally) in a positive or negative manner. This could be detected by a difference in the movement of the vocal cords because of the difference in tone. Or, you could measure someone’s interest or curiosity on a subject by looking for low-to-high inflection (questions) from their vocal cords as they read about that subject.
This could all be measured by a combination of ultrasound techniques and electrodes to measure muscle activity. I think this could be a really interesting technology if not just a cool science fair project.