At approximately 1351 central time, a Cessna 152 landed without incident at David Wayne Hooks Airport after the pilot occupying the left seat departed the airplane during descent near Prairie View. The flight instructor in the right seat landed without further incident. The aircraft operator and the flight instructor said the pilot scheduled flight instruction and said he had an ear operation and needed to see how his ears would feel at altitude before he went for an FAA medical certificate. He also stated that he was contemplating doing some aerial photography, and wanted to see how the aerial visibility was from a Cessna 152. During preflight, the private pilot requested to not wear the shoulder harness but the flight instructor advised him that he was required to wear the shoulder harness during takeoff and landings. Following the takeoff, the private pilot removed the shoulder harness. The airplane was flown to an altitude of 9,500 feet msl. At that time, the private pilot requested that the flight instructor demonstrate a steep left bank. The flight instructor performed a 45-degree bank turn to the left. While on the steep turn, the private pilot opened the left window, tuned the radio to the 121.5 MHz emergency frequency, opened the left door and exited the airplane. The flight instructor notified the air traffic controller that the pilot had exited the airplane. No discrepancies were found with the aircraft restraint system or the left cabin door.