Fist watch the Van den Berg film, Voice Production: The Vibrating Larynx in gorgeous black and white! It is in 4 parts on YouTube. You can stop near the beginning of part 4, when the "collar" is discussed.
You should understand the laryngeal adjustments and their linguistic functioning shown in the clips from the film in this slide.
Clips extracted from the film that are the most important,are shown in these slides.