Describe the difference in pressure against your cheeks when they were full of air versus when you released it. how were you able to release the air? in which direction did the air flow?

When they were full of air, then the Pressure was the Highest 'cause of the larger force under the specified area as compared to when we released it.

We decreased the area of our cheek, so pressure increased and air flows from the cheek (area of high pressure) to the atmosphere (Area of the Lower pressure).

Air flows from Cheek to the Outside of your mouth i.e., in open air.

Hope this helps!