What does the the noise button under the red seeing one do?

The "noise or soundwave" icon under the eye icon is for confusing prey. When you get close enough to prey, you can click that icon and confuse them. Confusing prey makes them stop and not attack. It is excellent for combat.

The button helps you find nearby animals to kill. it lasts for a couple seconds. the red dots are prey, the blue dots are the other players in the game.