Oh, that's not what... I... meant... Terry was just sitting there by himself because everybody's always afraid to talk to the prettiest girl, except this guy.
Silence is when there is no sound, so how can you have the " Sound of Silence? " I think he's trying communicate the idea of loneliness here, of being by ourselves now that we've lost our president, President Kennedy.
As yet I had spoken to no one, nor did anybody seem to take notice of me; I stood lonely enough: but to that feeling of isolation I was accustomed; it did not oppress me much.
People have seen this as we talk a lot about the crisis of loneliness and that that loneliness can lead to any number of health complications beyond just feeling like you're by yourself.