This is the sound in the cabin inside the car. Under the hood, nothing can be heard that other sounds are mixing, but you can hear the ticking (rattling) in idle gear. And if you add gas gently, the tickling (rattling, knocking) is faster, the more turns the faster the tickling (knocking) faster. You can hear them up to 1200 revolutions, then they mute but above 3000 thousand revs appear again.
This can only be heard inside the car. Do you have ideas what is this?