Noise
Noise is a game mechanic that is created from some buildings in Songs of Syx. Some building that would realistically generate a lot of sound can annoy any nearby citizens that walk within the sound's radius. Such as the activity of a grain brewery or the constant bashing of pickaxes against rocks and metal at a coal mine. In other words, someone walking into a noisy radius will receive an increase to their "noise" stat, which slightly lowers their happiness.
Noise can be viewed by using the environment map and toggling on the "noise" option. When enabled, the player can see cyan tiles emanating from certain buildings, as seen in the image below. Isolation of other buildings can somewhat muffle some noise.