Final answer:
The comic technique where characters secretly listen to other conversations is called eavesdropping, often leading to irony, suspense, or humor in literature and film.
Step-by-step explanation:
The comic technique where characters listen in on other conversations without the knowledge of the participants is known as eavesdropping. This is a common narrative device used in both literature and film to create irony, suspense, or humor. Often, this technique allows the audience to learn information that the characters in the dialogue are unaware of, leading to dramatic irony. An example of eavesdropping might feature a character hiding behind a curtain or door, or even utilizing technology to overhear a conversation critical to the plot. Such scenarios can substantially impact character development and the story's progression, as well as enhance the viewer's understanding of character dynamics and conflicts.