I've never heard it described anything like what you said, but the only sound that most units make is fan noise which varies based on load. It's less noticeable when the the load is high enough to keep the fan running all the time ...
I assume you're sure the sound is coming from the device (rather than, say, an attempt to announce detections on a Google Home device). There's no audible indication of detections on the device itself. Has your unit been making the noise from day 1, or did it start recently?
Perhaps you can make a recording of what you hear and send it to
sup...@camect.com. I'll see if I have any idea, and, if not, we'll send it to the factory to see what they have to say.