An electronic device with a fan assembly is disclosed. The fan assembly includes an impeller and an insert separated from the impeller by a gap. The fan assembly increases airflow by rotationally driving the impeller. For a sufficient rotational speed of the impeller, the airflow reaches a level that provides a force that displaces the insert. The displacement may include movement and/or compression of the insert. As a result of the displacement, the gap between the impeller and the insert increases. The increased gap reduces the pressure and associated noise that is otherwise caused by the airflow. When the rotational speed of the impeller reduces or ceases, the insert returns to its initial position. In this manner, the fan assembly includes a self-adjusting gap that changes based on the airflow.