What purpose does the repeated tapping sound st the door serve in edgar allan poe's "the raven"?

The purpose that the repeated tapping sound at the door serves in Edgar Allan Poe's "the raven" for is that It builds suspense.

Explanation:

"The Raven" by Edgar Allan Poe, uses assonance in the first stanza when he introduces the idea of somebody or something tapping at the door, "While I nodded, nearly napping, suddenly there came a tapping, / As of someone gently rapping, rapping at my chamber door" he uses different devices in this lines to generate expectation on the reader.

It builds suspense and makes the reader curious.