Somewhere I read or heard (and vaguely recall) that music is mathematical. Do you have any basic idea what is meant by the statement that "Music is mathematical"?

There's much in the relationship of Music and Math.
I believe a study in basic music theory beginning with notational values, pitch relationships and intervals (distance between two pitches[notes]) and chords (three or more notes played at the same time)might give you a basic understanding of music's relationship to math. Next would be Meter(the rhythm or beat of the notes and their values within each measure).

There is an excellent essay on this subject which goes much further than I can take you. It's about a 15 minute read but very informative.

Click Here

And then, if you're really interested, you might want to persue this sight.

Here

I hope this will be helpful to you.

Peace!

Paul (Piano1)

You'll also find a lot of clearly written material in Godel, Escher, Bach by Douglas Hofstadter. It's one of the themes interweaved into the wide-ranging narrative. Happy hunting! -- try the book's exceptionally complete index.

It does appear that I am going to have to rearrange my thinking cap (psyche myself up, too) before digesting the material in these links. Thanks.