Yeah, just dimensional theory shyt. Usually vision is the example. Think of it this way:
Let's say there's a one dimensional being. Try to describe or tell it to go "up" or "left/right" and it won't understand cause there is no "up" for it. Only forward and backward.
2D creature would understand and be able to go left/right but still wouldn't understand or be able to go up/down
We're 3D so we understand all of these. But imagine someone saying to shrink and expand your size... she's basically alluding to this with sound.
We can hear behind/in front/left/right/up down but a sound in the 4th dimension wouldn't be something we can hear. Physicists are apparently looking into capturing it.