Music can be art in the same sense as a painting. It kind of depends on intention and context though. Music has lots of uses, it's a way of communication, an artform, sonic wallpaper, a vehical to cram more commercials down your throat, a reason for social interaction, a way to heighten festivities, a way to connect with another spiritual world, a way to strengthen the vibe of another piece of art, simple entertainment and a lot more.
But yes, it can be art like a painting. With a painting, you can hang it on a wall and just have it there and see it in the corner of your eye as you walk by, just as music can be playing in the background while your attention is elsewhere but you still kind of notice it. But you can also sit in front of a painting and really look at it and get lost in it, like with music you can sit and listen and get totally lost in it. But you can also dance to it and loose yourself that way (which is kind of hard to do with a painting).
Damn, I suck at trying to find the proper words when talking about this...