Why does the human body change its voice when inhaling helium?

It is because the sound wave of sound must propagate through the medium, and the type, state and density of the medium will affect the propagation speed of sound wave. Human voice usually travels through the air. When the composition of air changes from 78% nitrogen and 265,438+0% oxygen to 80% helium and 20% oxygen, the density becomes one-third of that of normal air, and the speed of sound propagation is nearly three times faster because of this change, so the voice of people who inhale helium will become higher. This interesting phenomenon makes people who inhale helium scream and breathe. Helium is an inert gas, which is non-flammable, non-toxic, non-radioactive, naturally occurring and harmless to the environment. It is also the second most abundant substance in the universe besides hydrogen. However, its stock on the earth is very scarce.