How to avoid a thin, shaky voice when you are about to give a speech

Jackie Gartner-Schmidt is a speech-language pathologist at the University of Pittsburgh. She studied why people's voices tremble or even squeak when they get nervous. It's because our vocal cords close up as a protective response to stressful situations, so we don't accidentally inhale water. In the video above, filmed at a TEDx event, Gartner-Schmidt shows an exercise to open your vocal cords if you are nervous about having to speak in public.
From TED:
Hold up your index finger a few inches in front of your mouth. As you exhale steadily, make a “Wooooooo” noise (think: little kid pretending to be a ghost) for 5 to 10 seconds. Do this 5 to 10 times. (Watch her demonstrate it here.)
“This … essentially relaxes the vocal folds,” says Gartner-Schmidt. “It establishes breath and air flow and voice stability, which is the cornerstone of any strong, clear voice.”
Right before the next important occasion in which you have to speak — for work, for the toast you’re giving at a wedding, for a speech to a community board — take Gartner-Schmidt’s advice and “spend some time finding your best voice.”