The utility model relates to an audio cavity structure using a loudspeaker to emit supersonic waves belonging to the supersonic wave distance measurement technical field. According to the technical scheme provided by the utility model, the audio cavity structure comprises a housing and a loudspeaker disposed in the housing. The bottom end of the loudspeaker is disposed on the bottom part of the housing by a second loudspeaker fixing support, and the front end of the loudspeaker is connected with the housing by a first loudspeaker fixing support. The outer side of the first loudspeaker fixing support is provided with a screen, and a front audio cavity is formed between the first loudspeaker fixing support and the screen. A rear audio cavity can be formed between the first loudspeaker fixing support and the bottom wall of the housing, and is communicated with the front audio cavity by a leakage hole of the first loudspeaker fixing support. The audio cavity structure is advantageous in that the structure is compact, the transmission distances of the supersonic waves can be improved, the transmission angles of the supersonic waves can be increased, the interferences of the low and medium frequency sound waves can be reduced, the measurement accuracy can be improved, the application range is wide, and the use is safe and reliable.