I+knew+the+sound+well.+Many+a+night,+just+at+midnight,+when+all+the+world+slept,++it+has+welled+up+from+my+own+bosom,+deepening,+with+its+dreadful+echo,+the++terrors+that+distracted+me.

I knew the sound all too well. Many a night, just at midnight, when all the world slept, it has welled up from my own bosom, deepening, with its dreadful echo, the terrors that distracted me.
I think that this goes to show that the narrator in this story (the guy that killed the old man with the lazy eye) is very corrupt. Something is truly wrong with him when he says that he has terrors inside of him that distract him. This, to me, is very similar to a schizophrenic (or however you spell it) person. They, too, have voices inside of them telling them to kill people, do bad things, etc. a severe mental disorder characterized by some, but not necessarily all, of the following features: emotional blunting, intellectual deterioration, social isolation, disorganized speech and behavior, delusions, and hallucinations.
 * I looked up the definition of schizophrenia on Dictionary.com and here's what I got:**

I really think that the narrator has something seriously wrong with him. The only answer that I have would be schizophrenia. 1197303067