Hello, The frequency sound is determined by the frequency shock wave of the head and the 40K and 80K probes are high frequency, so the body of the person being touched will have the frequency sound. Also,The frequency sound is less perceptible in places with more flesh, and the closer to the bones, the more obvious the perception. If you are sensitive to sound, you can adjust the energy of the fat-blasting head to a lower level or reduce the operation time, use the radio frequency head and negative pressure head more often, and slowly adapt.