The right white noise for sleep has no beginning and no end. You should not be able to tell when it restarts.
We listened to fan motors and to digital machines in a quiet room, which is where a loop shows itself. Pitch that stays put matters more than a library of rain forests.
Fan or file
A fan makes noise by moving air. It does not loop. It can tick, and the pitch is whatever the motor is. A digital machine can be smoother and can still betray a short recording if you lie there waiting for it.
- Listen in the dark for a full minute before you trust it.
- A pitch that does not wander as the motor warms.
- A physical knob if you wake at night and need it lower.
- No bright LEDs aimed at the pillow.
A sound with a seam will find you on the night you most need to sleep.
Setting it
Put it where it fills the room and leave the volume alone for a few nights. Chasing the perfect level every evening keeps you awake more than the traffic did.
Choose the machine you cannot hear thinking. That is non-looping in practice.
