Cicada chorus
Many cicadas calling at once — a summer sound so constant it becomes the texture of the air.
A cicada chorus in a dream is the dream's image of a sound that is so constant the listener stops hearing it as sound and starts hearing it as the texture of the air. The cicadas are individual; the chorus is a whole season. The dream brings the chorus when something in your life — a long-running complaint, a low background of opinion, an ambient pressure — has been continuous for long enough to stop being noticed. A chorus heard with attention is the dream telling you the ambient noise is still real and is shaping the room. A chorus that has fallen silent in the night is the dream noting that the steady season-sound, taken for granted while it lasted, is over, and the silence it left will not be missed by those who never heard it as anything.