The dryer vent on the back of my house is making a gurgling noie when i dry clothes?

my dryer has not been drying properly for months. it heats up, but does not let the steam buildup out of the dryer, so it takes a very long time to dry. Just yesterday, i was out in the backyard with the kids and i notices a gurgling sound coming from the dryer vent outside my house, and i had just put a load of clothes to dry. If i need to check for blockages, how do i do so? Thank you for any help, and as a single parent, i am trying to get around having a repairman come!