The pilot arrived overhead the airfield from the north-east and joined crosswind for Runway 09. He heard several partial radio calls on the SAFETYCOM frequency but could not identify the source of any of these transmissions. On final approach, the pilot stated that he was high on his approach path and that his speed seemed less stable than usual but he did not perform a go-around. Upon landing, the aircraft settled lower than expected, pitched nose-down and slid to a halt. The pilot and passenger were uninjured during the gear-up landing and vacated the aircraft in the normal way. The pilot attributed the incident to his failure to action the before-landing checklist, possibly because he was distracted by the partial radio transmissions.