The bolded words "pulse" and "keener" in the excerpt from "Sympathy" by Paul Laurence Dunbar utilize the sound device known as alliteration. Alliteration is the repetition of consonant sounds at the beginning of words in close proximity to create a rhythmic and melodic effect. In this case, the repeated "p" sound in "pulse" and the repeated "k" sound in "keener" create a pleasing and musical quality to the line.