In poetry, personification gives human characteristics to an object or idea. To emphasize the speaker's isolation, Simon uses personification by having him speak directly to "darkness, my old friend." The speaker desires to encourage people to find meaning in their lives beyond commercial culture, but no one will listen, except for the darkness he awakens to after dreaming of a chance to address them. The second line, "I've come to talk with you again," tells readers that these nighttime conversations are habitual, further emphasizing the speaker's status as an outcast.
A simile is a poetic device where the author describes something through a comparison, using the words "like" or "as." In "The Sound of Silence," the speaker uses a simile when he states that "silence like a cancer grows." The people in his dream worship material culture at the expense of relationships with others, and the comparison of their silence to cancer emphasizes the destructiveness of this lifestyle. The speaker uses another simile when he says that although he pleads with them to listen, "my words like silent raindrops fell." Like rain, his pleas fall quietly and unnoticed.
Rhyme is the use of similar sounds to create unity within a poem or song. In "The Sound of Silence," Simon uses end rhyme, a type of rhyme that occurs when lines end with the same sound. For example, the first verse contains end rhyme through the words "friend" and "again," "creeping" and "sleeping" and "brain" and "remains." The final line of the verse ends with the word "silence," but no corresponding rhyming line, creating a beat of actual silence in its absence.
The University of California Stanislaus defines paradox as "an apparent contradiction that is nonetheless true." It might seem impossible that the people in the song can be "talking without speaking" or "hearing without listening," since on the surface, these words appear to be synonyms. However, Simon uses these paradoxes to imply that the people's relationships and conversations are so superficial and limited that they fail to have any connection or deeper interaction. In this case, paradox makes us think about the level of alienation these subjects experience.
Tone is the speaker's attitude toward the subject of a poem. In "The Sound of Silence," the speaker feels he has an important message to deliver to the people entrenched in materialism, but they are too busy worshiping "the neon god" of culture to care. The speaker's tone can therefore be described as solemn and disappointed. From the fact that only darkness will listen to his message to the people's ultimate rejection, it is clear that he is saddened by the narrowness of their lives and that they are unable to look for something deeper.