It's not normal unless your fan vents are blocked. Use an air blower and try to clean the laptop vents with immense air. In case this doesn't fix it then your fan may be faulty or touching some object that is creating this sound. You can also try to use a cooling laptop fan, easily available on Amazon.
Heat plays a big factor but laptops are rugged devices that do not malfunction with heat.
That's not entirely true. It is a tried and tested method I have applied and my fellow colleagues have as well. Laptops are strongly built and the chances to damage any part is nominal. In majority of the cases it doesn't affect