Abstract: Sensitivity analysis plays an important role in assessing the importance of parameters and calculating the uncertainty. Mach number sensitivity analysis of cavity noise at subsonic, transonic and supersonic speed has been investigated by wind tunnel experiments in this study. At subsonic speed, the Mach number is changed by adjusting the opening of the valve, and the nominal increment of the Mach number is 0.01.At supersonic speed, the continuous change of the Mach number is achieved by changing the angle of attack of the model, and the increment of angle of attack is 1 degree. The experimental results show that the fluctuating pressure coefficient at the rear of the cavity increases with the increase of the Mach number at the subsonic speed, while decreases with the increase of the Mach number at the supersonic speed. At transonic speed, the fluctuating pressure coefficient has the largest sensitivity derivative to the Mach number. In the case of modal switching, the derivative of St to Mach number for the dominant acoustic mode is negative. The peak value of the dominant acoustic mode's power spectral density increases with the increase of Mach number at subsonic speed, while decreases at supersonic speed. The obtained sensitivity results can be used not only for the uncertainty assessment of the aerodynamic noise load in the embedded weapon bay, but also for a better understanding of the cavity noise characteristics.