Die down
Definition 1 of 3
Pro Tip 1/3Intensity Reduction
Used to describe a decrease in strength, noise, or activity levels. 
The shouting eventually died down, and everyone went back to work.
Pro Tip 2/3Common After Events
Often follows events causing excitement or disturbance. 
When the concert ended, the crowds slowly died down.
Pro Tip 3/3Emotional Calm
Can refer to people's feelings becoming less agitated. 
After the heated argument, emotions started to die down.