The poem begins with a listener. The speaker says they hear "so much by chance," as if sounds simply drift in without being invited. Then come three odd, vivid images: "a fat plum of a bark," which turns a dog's bark into something round and ripe, and "a passionate vapor," which feels warm, breathy and hard to pin down. The senses blur here, so sound takes on taste, shape and temperature.
The last two lines change the tone. A figure "with ash and dagger" has "moved in under my bed." The playful, sensual listening suddenly becomes unsettling. The speaker doesn't say who this is or whether it's real, which makes it feel like a half-asleep fear, or a night noise the mind turns into a person. The title, "Acute," fits: the speaker's hearing is sharp, maybe too sharp. The mood moves from curious and pleasant to quietly menacing, and the poem leaves us in that uneasy dark without any explanation.