The science and the art of tones, or musical sounds, i. e.,
   sounds of higher or lower pitch, begotten of uniform and synchronous
   vibrations, as of a string at various degrees of tension; the science
   of harmonical tones which treats of the principles of harmony, or the
   properties, dependences, and relations of tones to each other; the art
   of combining tones in a manner to please the ear.