The horror in this story emerges from the vivid descriptive imagery that the narrator uses to describe how he stalks the old man at night. While he does not use smell or taste imagery, he does describe standing still in a creepy way night after night in the darkness, watching and listening to the old man. Then he says,
I resolved to open a little—a very, very little crevice in the lantern. So I opened it—you cannot imagine how stealthily, stealthily—until, at length a simple dim ray, like the thread of the spider, shot from out the crevice and fell full upon the vulture eye. It was open—wide, wide open...all a dull blue, with a hideous veil over it that chilled the very marrow in my bones
We can imagine the narrator standing still in the darkness for a long time and the old man lying awake, terrified from sensing someone in the room. The narrator conveys a sense of touch as he describes how slowly and carefully he opens the lantern and shows the single streak of light coming from the lantern to touch the "vulture eye." We can feel the sensation of cold, too, as the narrator reacts to the eye with a "chill" that enters his bones.
Near the end of the story, the narrator uses touch imagery to describe how he tries to mask the sound he imagines he hears of the dead man's heart, beating louder and louder:
I paced the floor to and fro with heavy strides, as if excited to fury by the observations of the men—but the noise steadily increased. Oh God! what could I do?...I swung the chair upon which I had been sitting, and grated it upon the boards, but the noise arose over all and continually increased.
We can feel the "heavy strides" hitting the floorboards and the sensation of the grating of the chair on the floor as he tries to muffle the sound of the heart. We can also feel the motions of the narrator's arm and shoulder muscles as he swings the chair.
Concrete descriptive imagery puts us into a scene and helps us feel as if we are there. This raises our own emotional level to a higher pitch than merely using abstract words would. Poe was a master at using specific descriptions to raise his reader's sense of terror.