Throat tension when you're nervous or caffeinated narrows your vocal folds and strains your voice. A simple warm-up that turns the "sh" sound into a "z" gets your folds vibrating freely, so you sound more resonant and confident.
Chapters
Most people push a lot, push too much air over the vocal folds, and they end up straining the throat. The throat becomes narrow. So you mentioned the feeling of when you drink coffee, the feeling of narrowness in the throat. So that's a somatic sensation that if we get perhaps nervous before we speak. So by warming the voice up and using the correct muscles to do that, it's gonna keep the larynx and the throat really nice and open. And relax. Now, to feel the resonance, which is basically the vocal folds moving together, they're connecting together very quickly, and that's causing the vibration or the phonation, if you like. We're going to change that sh into a j. So we're going to go from a sh to a zzz.