Helium

Helium is inert against the human body. However, without putting in oxygen, the body may suffocate. Chiyuri, are you okay?

The speed of sound becomes faster when using helium because helium is less dense than air. Thus, the frequency goes up. You see, the human ear doesn't use wavelength to sense pitch, but uses frequency. So, it sounds like your voice gets a higher pitch after breathing helium.

That's awfully boring for the last experiment.

Our last experiment for today explains why breathing helium changes your voice.

Ughh......!?

*She won't die from this.

She's dead......