My favorite definition of music is the one given by Schopenhauer:

"Absolutely direct experience of the will is impossible, because it will always be mediated by time, but in first-personal experience of volition and the experience of music the thing in itself is no longer veiled by our other forms of cognitive conditioning."

There's also a less poetic, but I believe a more accurate definition in the blog you've linked:

"Music is a hidden arithmetic exercise of the soul, which doesn't know that it is counting." (Gottfried Leibniz)