Not 100% sure of the details but I think it’s more like a digital pwm system. I had dimmers installed when we rewired our house and I thought they were rubbish

Not 100% sure of the details but I think it’s more like a digital pwm system. I had dimmers installed when we rewired our house and I thought they were rubbish. Replaced those with Varilight v-pro and they were noisy. Discovered that I could switch between leading edge and trailing edge modes (or something like that) and the sound went away. Love them now.