Details
The sound begins with a subtle hissing noise, which is the sound of a tank being opened. The gas inside, helium, starts to flow. Then, the distinct sound of a balloon being stretched and prepared for inflation enters the scene. The hissing noise gets slightly louder as the nozzle of the tank is inserted into the mouth of the balloon. As helium fills the balloon, the hissing gets subdued and the crinkling sound of the balloon growing larger is audible. The balloon expands, and the sound of rubber stretching fills the audio. Then, the balloon is tied off, and a final, satisfying pop sound indicates it's now filled with helium. The last sound is of the inflated balloon bobbing up into the air, carried by the helium inside.
