Try starting it up in "Safe Mode" and see if you get the noise in there or not. If you don't, that means it is software related. So then I would check the device for bad apps, viruses, malware, etc.
If, however, it still makes the noise in "Safe Mode" then it is likely hardware and you need to contact the manufacturer (if it is under warranty) or a local tech to see about fixing it.
To get into "Safe Mode" please do the following.
1. First turn off the tablet.
2. Next press and hold "Power" until you see the manufacturers logo on the screen, then release the power button.
3. "Quickly" press "Volume Down" and hold it for few seconds until you see the message "Safe mode: ON" or something similar.
4. If you wanted disable it, simply...