Ok /vp/, help me out
I'm finally playing the game and I've noticed something odd. Sometimes, just after sending out a Pokémon, the game does a low "whoosh" like sound. It sometimes blends in with longer cries but some other times it's very noticeable, like it was signaling something.

I've then noticed it isn't random, but rather tied to specific Pokémon like my Flapple or my Orbeetle.

Searching online, it seems it's mostly tied to Pokémon that float but some claim Pokémon such as Rookidee and Rolycoly cause it as well

What is this sound? Why does it exist? Have there been threads before discussing it?