What are the poetic devices used in the poem "The Listeners" by Walter de la Mare?

The imageryof silence is significant. Walter de la Mare fills the house with images of absence, silence, and even death. The listeners are "phantoms." Taken literally, this could mean they are dead or absent, but it could also imply they are there in the house and just refuse to answer the Traveller. Even though the Traveller might think people are actually home, those people might as well be phantoms because they refuse to answer...

The imagery of silence is significant. Walter de la Mare fills the house with images of absence, silence, and even death. The listeners are "phantoms." Taken literally, this could mean they are dead or absent, but it could also imply they are there in the house and just refuse to answer the Traveller. Even though the Traveller might think people are actually home, those people might as well be phantoms because they refuse to answer him. The listeners are in the "quiet of the moonlight" and the Traveller is the "voice from the world of men." This imagery suggests the listeners are part of nature itself and the traveler is a lone man asking questions but receiving no replies. The latter is more philosophical because it suggests a man asking questions by himself.

Taken literally, this is a man asking for communication at the door of a house. One could interpret the poem in a broader metaphorical way, though, by arguing the poem shows how every individual seeks communication and acknowledgment from others. It is a social yearning we all have. It also describes the experience of how every individual asks questions (of other people, God, or nature) but does not always receive a response. So, metaphorically speaking, the Traveler is anyone who seeks these things. In this way, the entire poem is a literary device: a metaphor of how every individual reaches out for answers.

As the Traveler leaves, the listeners wait for the noise to fade away. The poet uses alliteration to suggest the sound of a light breeze, whispering, or a susurration:

And how the silence surged softly backward