They are easy peasy @mc9 I had two in two weeks.. if you are lazy like me it is a grand excuse to lie still and maybe have a snooze. They place 'packing' around your head to keep it in place and they give you ear plugs to kill some of the noise and they then put earphones on you. You are aware of the noise changing. I tried to count the clicks but of course I couldn't!!! Like Brunneria said I think I dozed off... if you snore they wont hear you for the noise the machine makes