I agree: music matters, and it matters ever more in times where those in power have none of it. As Shakespeare put it " The man that hath no music in himself, Nor is not moved with concord of sweet sounds, Is fit for treasons, stratagems, and spoils; The motions of his spirit are dull as night, And his affections dark as Erebus"
As far as definitions of music are concerned, I'd direct interested parties to Tomas Turino's excellent book Music as Social Life (Turino, T. (2008). Music as social life : the politics of participation. London: University of Chicago Press), ideas he covered in brief in a later paper (Turino, T. (2009). Four Fields of Music Making and Sustainable Living. The World of Music, 51(1), 95-117). As for my own ideas about music — they evolve, but I'd suggest two papers that present ideas point in the direction of definitions:
Cross, I. (2012). Cognitive Science and the Cultural Nature of Music. Topics in Cognitive Science, 4(4), 668-677.
Cross, I. (2014). Music and communication in music psychology. Psychology of Music, 42(6), 809-819.
Ian Cross