What is the density of helium compared to air? As a result of #1, what is the speed in which air travel throughs helium compared to air When #2 happens, does the tone go deeper?
Helium
Helium is less dense than air. Sound travels more quickly through helium than it does through air.  When sound travels more quickly, the tone of it raises and sounds higher.
Chemical element with atomic number 2
Does the density of helium cause voices to sound deeper?