Basically as the title says. We have semi frequent power outages where I live. The noise machine in my daughter’s room goes out and wakes her up. If I were to buy a USB powered one, plug it into a power bank like one of those 10000ma ones you get for charging cell phones, would it have continuous power. Basically like a cheap UPS
Some you can access via the Ethernet and change the settings. Got one of those units and then see if it has the option.
Here’s just one tutorial: https://linux-tips.com/t/disabling-ups-beep-under-linux/592
There are many others. Good in places where medical equipment keeps you alive and sleeping.