Blowing air into a whistle causes air to vibrate inside the whistle.
An ocarina is a multiple-tone whistle.
Blowing air into an ocarina causes air to vibrate inside the ocarina.
What happens to the air inside an ocarina when you blow into it?

[1] It expands
[2] evaporation
[3] moves
[4] waves
[5] Temperature
[6] vibrates
[7] It decreases
[8] friction