Music or ambient sounds for meditation? My own experience with meditation is that it works best when I'm alone and it's quiet. But in the dharma center they sell lot of cd's and many of them are titled "for meditation". 

Is it absolutely and definitely not "Comme il faut" to meditate with music? Is this music they sell for meditation more for rituals etc? Or is there some kinds of music that can be used for meditation? By "music" I don't necessarily mean melodic compositions, but ambient sounds like fex theta waves. Any experiences and/or advice?
If one is using music in order to be able to e.g. concentrate better, then it might not be the best solution. In time it could become a "crutch". 

There are many views and discussions about this and ultimately it comes down to personal preference. For some meditators it might be okay to use a crutch in the beginning, which they can later do away with.

For others, they might prefer to learn meditation or to meditate in silence. Their is no definitive answer to this.