A. The figure of speech in line 11 is a metaphor.
B. The metaphor is relevant in this poem because it helps create a vivid and imaginative description. By comparing the speaker's heart to a small muffled drum that "looks through the glass windows," the poet is using figurative language to convey the idea that the speaker's heart feels trapped or confined, longing to break free from its confines and express its emotions. The image of the heart looking through the glass windows suggests a sense of longing and yearning for release and connection. The metaphor adds depth and emotional resonance to the poem, allowing the reader to understand and empathize with the speaker's inner turmoil.