Yes it's true, but that doesn't last very long. It creates a compression of the molecules during exactly half of each vibe, and during the other half, it leans the other way, and the molecules spread out in what's called a "rarefaction" a region of lower-than-normal pressure. This 'train' of compressions and rarefactions is what travels through the air, away from the vibrating object, and it's what some people often call a "sound wave".
Logically, it would be B
Polka dot patterns are just a simple pattern with rhythm and symmetry
I'm not sure what piece you're talking about, maybe you could include a picture of the piece
but in the treble clef the e's are on the bottom line, and top space
if it's flat it'll have a little squished 'b' next to it
a flat e is also a sharp (#) d
