In the poem "the raven," what information does the poet withhold from the reader to create suspense?

which word the bird repeats
what time of day it is
who the woman lenore is
what is making the noise

In the poem "The Raven," the information that the poet withholds from the reader to create suspense is what is making the noise.
First, the narrator thinks it's just branches hitting the windows of his room. Then, he hears a knock on the door, but there's no one there. In the end, we find out the noise is coming from the bird, a raven.