Throughout edgar allan poe’s poem, the raven utters only “nevermore.” how does the repetition of this word affect the speaker?

In the beginning, when the narrator first hears the Raven saying that word, he is confused, but that is it. The more the Raven repeats the word, the more scared and terrified the narrator is, because he is realizing that he will never get to see his beloved again. In the end, he goes completely mad with fear, grief, and hatred towards the bird and begs it to leave, but the Raven answers only one word - Nevermore.