LullbeeDedicated sound machines are fine products. They are also sixty dollars of hardware that does one thing, lives on one shelf, and stays home when the family does not. The honest question is not which is better in a lab. It is what a phone needs in order to do the same job, because the phone is already in the room.
What a machine gets right
It plays all night without interruption, it does not light up the nursery, and its volume never changes unless someone changes it. Those are real virtues, and any phone setup has to match them.
What the phone needs
True seamless loops. A sound file that fades or clicks at its loop point wakes babies at the exact moment nobody is watching. Screen-off playback. The audio must keep playing with the display dark and the phone locked, no glowing screen in the nursery. Do-not-disturb. A notification chime punching through rain at 2am undoes everything. Consistent loudness. Every track at the same gentle level, so switching sounds never startles.
Where the phone simply wins
Grandma's house. The hotel crib. The back seat. The stroller. Sleep does not only happen in the one room where the machine lives, and the phone is the only sound source that is always where the baby is. A library of hundreds of sounds instead of ten is a pleasant bonus on top.
Lullbee was built around exactly that checklist, seamless loops, screen-off playback, matched loudness, everywhere the family goes.