Once powered on the unit emits a whining noise

so it doesn't blend into the background like a solid steady noise would do

My favorite feature is being able to disable the alarm noise.

Both units started emitting a loud beeping noise and had a strong acrid smell from the transformer area.

But it makes an unbearable high-pitched noise

Super loud beeping noise and totally dead.

My biggest complaint is the noise

Also, when plugged in, there was a high-pitched noise, very faint

In a power outage test, I feel like the water is turned on on and off rapidly, making scary noise in the pipes

4th... and my primary reason for returning the units: when plugged in, these units emit a high frequency exceedingly annoying noise, which I can detect clear across the room

It's impossible to disable the "low battery warning" annoying constant loud beeping noise

the UPS makes this annoying noise

Super annoying high pitched motor noise