In this study, it is experimentally investigated how bell acoustics are influenced by the internal cavity of the bell and the gap between the bell bottom and the floor. Acoustic transmission function and natural frequency of a test bell are measured and analysed. Experimental study is conducted to evaluated how the resonance effect influences the bell sound and how the bell sound is different according to the striking condition and the measurement direction. Acoustic resonance frequency of the cavity-gap system is predicted by boundary element analysis using SYSNOIS and the validity of the predicted result is verified by experiment. The result of the study could be applied to determine the optimal gap size which makes the bell sound strong and long.