Ralph is the "Mass Murderer". If he only just spawned in the sound will change. He is only seen in the First Maze, but he can sometimes glitch into The Green/Second Maze. 

The only known way to out run his is to:

Never run away from him in the hallway. He is faster then you, and he will get to you quickly like that. But if you constantly turn onto corners, he will slow down, as he can't turn very fast.

It is possible to dodge his Katana by going the opposite way he swung his Katana. But it's not very easy, so I suggest beginners run away from him.