Hello FARJADH.
Thank you for using Apple Support Communities. You mentioned that you're hearing sounds coming from the inside of your iPad. If so, this doesn't sound like expected behavior. If you restart your iPad, are you still able to hear sounds coming from the inside of your iPad?
Restart your iPad - Apple Support
If you're still hearing sounds, even after a restart, you might want to consider reaching out to Apple Support. They might have to get your device physically evaluated to make sure everything is properly working. Just in case, you can use the link below to reach them:
Get Support - Apple
Thank you for using Apple Support Communities. Cheers.