So, we have a new noise in the house. When we run the water, flush the toilet, run the dishwasher, etc. basically, whenever water goes into the main drain there is a noise that I can only describe as a "thump, thump, thump..." or "glug, glug, glug" that seems to be concentrated around the air vent that is in the foundation. This vent is off of the main sewer line in the basement and goes out the side of the house under the bathroom. This noise is new. It is pretty loud and resonates throughout the area around the bathroom, kitchen and home office.

I'm in NY, it is quite cold right now but it wasn't earlier in the week when this noise first started...I think I first noticed it on Tuesday.

This past weekend, the bathroom sink was slow so it was snaked and a clog was removed. Not sure if this is anyway related but thought I'd mention it just in case.

So...any ideas? Do I need to worry about this?