Krakin

There are different molecules of different elements that make up "air". I'd say that all these different molecules transfer different notes than the others.

Okay, let's think of 'air' as a single molecule, bad wording on my part.

Or think of waves in a lake. You can throw two rocks to two locations and the resulting waves will not deteriorate when met by one another, however, the molecule H2O on the surface can only have one instant of motion at one time.