It's an interesting vignette. I'm not sure I would call it "frightening" or anything, but as an addition to The Strange Case of M. Valdemar, it's worth listening to. Poe is being creative in attempting to posit another paradigm of the world. I'm sure in its day it probably came off rather irreverent and controversial. One of the strongest points is how well he addresses topics in physics and metaphysics which are so easily overlooked. The narrator has good pronunciation and diction.