The Cry Sensor should be activated by default as soon as the Moonie is switched on. After a while (in our case: after an hour), the sound switches off automatically. And then it switches on again automatically when the baby starts to cry. No separate button or additional equipment is required, at least in our case. As soon as the Moonie switches off after an hour, the cry sensor is automatically activated. And in the morning, we actively switch the Moonie off again.