What causes the water in the toilet to bubble? As well as sound from all drains?

What causes a fixture to bubble is the back pressure sending a bubble of sewer gas ahead of it when it bounces back after hitting a partial blockage.
If all the drains talk back to you that indeicates the problem's in the house main or in the sewer line itself. The solution is to snake out the drain lines. Good luck, Tom

Tom, could this be a blocked vent stack? You have the fix for that I'm sure.

Bob

Tom, could this be a blocked vent stack? You have the fix for that I'm sure.

Bob
Blocked vents=gurgles
Blocked drains produce bubbles.
The complaint concerns bubbles. Cheers, Tom