We have 3 young kids in the range from 2 to 5 years old. We use white noise heavily for our kids sleep. It isolates them from the noises we make around the house.
For this purpose I recommend "LectroFan" devices. We have like 5 "LectroFan Evos" in our's and our kids' bedrooms. They just work, no apps, no upgrades, no LEDs blinking, and thank god, no screens. These devices are worth their amount in gold.
On the phone I recommend using iOS built-in white noise feature. We use it when travelling by car, and our kids sleep in their seats. When we turn the white noise on they stop talking and it quickly lulls them into sleep.
replies(4):