Final answer:
A piece of dialogue directed to the audience that other characters aren't supposed to hear is called a soliloquy. This technique is used in theatre to provide insight into a character's thoughts and emotions, affecting the overall experience of the play for the audience.
Step-by-step explanation:
A piece of dialogue directed toward the audience that other characters on the stage are not supposed to hear is an example of soliloquy. In theatre, this technique connects the audience to the inner thoughts of a character, which may reveal backstory, secrets, or personal motivations. The play Hamlet by William Shakespeare offers an example of soliloquy, enhancing the audience's understanding of Hamlet's internal conflict. Unlike dialogue between characters, which is meant for all on stage to hear, a soliloquy is a powerful narrative device that speaks directly to the audience and is crucial for the development of the plot and depth of the character. This form of dialogue is especially significant to how audience members experience the play, making it a key element of theatre production and performance.