When starting Chapter 2, after a stressful night, you can calm yourself down. Depending on the situation, there will be a ghastly sound and a moving glowing circle will appear on the screen. You have to keep the dot with L3 inside until it fills in order to stop the noise.
This trophy will pop as soon as you enter the bedroom again, with the next auto-save. Don't worry if you miss this opportunity since there will be five chances in total to calm yourself down.