Our physical body can only feel up to about 1,000 Hz. But the Healy can use up to 1 MHz. First try to increase the intensity until you feel a slight tingling. It also depends on which program you use. Some programs have a higher current intensity than others. The ear electrode programs usually work with low amperages. Some people are very electrosensitive, so you can switch to a higher current in the HealAdvisor app under Settings -> Healy Configuration. Please make sure that the cables and electrodes are connected properly and that current is flowing as well. You can tell if current is flowing when the circle indicating progress turns white.