The warriors celebrate in the king's mead hall Heorot in an attempt to lure Grendel out. When the monster attacks, Beowulf fights him nude and unarmed (it is revealed that he is invulnerable to man-made weapons). In the fight, Beowulf discovers Grendel has hypersensitive hearing, which is why he attacks Hrothgar's celebrations (the noise from the mead hall is painful to him). After his left eardrum is ruptured, Grendel shrinks in size and, while trying to escape, Beowulf restrains him and uses the door of the hall to sever the monster's arm. To thank him for defeating the monster, Hrothgar gives Beowulf his golden drinking horn, which commemorates his victory over the dragon Fafnir.