The pilot of a retractable landing gear equipped airplane reported that he landed with the landing gear retracted. He further reported that the airplane slid about 100 feet to a stop near the right edge of the runway. The fuselage sustained substantial damage. The pilot reported no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation. The Federal Aviation Administration (FAA) Aviation Safety Inspector assigned to the accident, by coincidence, was already at the accident airport for an unrelated event. The inspector observed the landing gear retracted into the wheel wells and observed the landing gear handle in the up position. He further reported that the pilot was using a "noise cancelling headset." According to the inspector, the landing gear warning horn was not designed to sound through the headset/ intercom system, but would be audible in the cockpit. He reported that during the airplane recovery process the landing gear handle was moved to the down position and the landing gear extended and locked normally. The FAA Special Airworthiness Information Bulletin (SAIB), CE-16-08, Noise Cancelling Headsets, in part states: "In many cases, pilots are using the noise cancelling headsets as supplementary equipment during operations. When wearing these headsets, the pilot may be unaware of environmental sounds and audible warning annunciations in the cockpit that do not come through the intercom system." The FAA SAIB recommends that general aviation pilots and operators: • Become familiar with the safety information in FAA InFO 0700 • Elect to find other solutions to discern such alarms or sounds, or discontinue using these headsets if any audible alarms or environmental sounds cannot be discerned while wearing a noise cancelling headset. The pilot did not report whether or not he had heard the landing gear warning horn prior to landing.