So, any resolution on what it was? Seems like this is the type of thing that could become an urban legend, if not resolved.

I feel like I forgot the exact episode I was on. But it was probably the first episode of Season 7, as I was on the fourth episode one hour later when I stopped and started wondering about what that noise was, before coming here to check. We should do a Seinfeld Philly watching party somewhere!

Came here just to post this and I was glad I was not the only one wondering about this. I was watching Seinfeld which was a bit loud, but the noise kept becoming ever louder and louder. By the time I would have felt I need to pause and go check what is happening, it stopped. Very spooky. Does anyone have a high quality recording of the sound? Maybe someone will have a video of it by tomorrow? Feeling very uncomfortable not knowing what just happened here.