Pop, a genre whose variety is often limited to the fast-paced whines of synthesizers and staccato cymbals, is a form of music that is heavily based on the strength of the beat and the rhythm of the words. For this reason, it is a genre that appears bereft of anything more than “skin-deep” conceptions of callow hyper-sensitivity. But in Katy Perry's album “Teenage Dream,” there is more to be found.