`  :::Hello, sorry to sound like your teacher, but I would consider ``Performance practice of Sacred Harp music`` to be bad English prose.  The music is being performed, not practiced, so to say ``practice of Sacred Harp music`` is misleading to the reader.    :::There's really no reason not to use a colon in a title; it's common in professional scholarship, even if not so common on WP.  Yours sincerely,   `