Meaning of "the sound of silence?"?

I think the neon god is the TV set and it's a lament about how mass market entertainment culture is inhumane because it alienates people from their community and from real life by isolating them; the sound of the TV and the silence of people listening to it instead of getting together and talking and interacting socially is the sound of silence. The words of the prophets are written on the subway walls = graffiti, which is sometimes thought of as subversive as it is the often angry and rebellious expression of marginalized people who are not so pacified by the TV set and mainstream mass-market culture.