Those wavelengths will have associated frequencies given by . The speed of sound is determined by the gas that is filling
the resonant cavities. If the person has inhaled helium, then the speed of sound will be much higher than normal, since
the speed of sound waves in helium is about 3 times that in air. Thus the person’s frequencies will go up about a factor of
3.This is about a 1.5 octave shift, and so the person sounds very high pitched.