Looks like a Finnish M40/M41 machine gun cupola.
Most of the holes appear to be 75mm impacts.
As for loud, not as loud as standard firing due to the machine gun muzzle being outside the pillbox.
interesting
re “As for loud, not as loud as standard firing due to the machine gun muzzle being outside the pillbox” - I think they meant to be inside the ‘cake” when it was being shelled. :)