noises from bathtub

recently in our top floor bathroom when you flush the toilet there is a gurgling sound from the drain of the bathtub....any ideas what is going on???

gurgle

Must be a restriction downstream of the connection between the two.

Or the drain is trying to breathe some air....Check the vent too.

vent

how do i check the vent.....or......what do i do with the vent????

noise

Go on the roof to that vent that is gurgling and have someone flush that toilet and listen for gurgling. If it gurgles, the drain is partially plugged. And that means you need to clean out the sewer. If you don't hear any water flowing , then the vent may be plugged. It's not likely but it could be.