 The Eustachian tube is a tube that connects the back of the nose with the ear. Its job is to keep the pressure on the inside of the eardrum close to the pressure outside the eardrum, so that the eardrum can vibrate properly. Usually this tube is closed, but it opens briefly during swallowing. In the condition called patulous eustachian tube, this tube is open all the time. This is a benign condition but it can be very bothersome to patients. 