PURPOSE: To demonstrate the rise in frequency of vocal formants due to the increase in the speed of sound in a light gas.

DESCRIPTION: Snort a lungfull of helium from a newly filled helium balloon and talk and sing normally. Your voice takes on a squeaky "Donald Duck" character due to the increase in frequency of your vocal formants.

SUGGESTIONS: Take a couple of big breaths of air first to get plenty of oxygen, then breath out completely before inhaling the helium.

EQUIPMENT: Tank of helium with regulator and a large balloon.

SETUP TIME: 15 minutes

KEYWORDS: helium voice vocal formants