While not Shoegaze, the first time I realized my inner dialogue had stopped completely for a few seconds was after the first time I listened to Washing Machine (the song, not the album, though I was listening to the album in full) by Sonic Youth. Up until then I had never though that'd be possible: I always assumed we all had an inner dialogue going on all the time (I later learned some people don't have this at all, which I find intriguing, probably as intriguing as they find that some people always have one!).