Acoustic panels need to be attached to the walls of your room. They do not allow the sound waves in their path to pass through. Acoustic panels have foam that dampens and absorbs the sound waves. Therefore, when outside noise waves pierce the walls of your room, their magnitude drops slightly due to the walls. Then the acoustic panels absorb the rest of the magnitude of the sound waves and do not let the sound wave pass through. The greater the thickness of the acoustic panels, the more effective they will be in blocking the noise. In fact, it stops the sound inside your room from escaping outside.