Abstract: Noise radiated from different jets are similar. For a given fluid, the spectrum of jet noise shifts toward higher frequency with increasing jet velocity and decreasing jet size. Therefore, the A-weighting sound pressure of jet noise is dependent on jet size and jet velocity. In the paper, a continuous A-weighting function is used to calculate the A-weighting sound pressure of jet noise and the increasing of noise reduction with the increasing of jet stagnation pressure or Mach number is obtained.