Carpeted floor promotes less reverberation of sound between the ceiling and floor. Add a thick rug over wood floors. If you already have carpet but it is thin, try adding a rug that covers any wide, open area of the floor. To contain sound for a short-term project, add temporary sound absorbers like moving blankets to floors and walls.
Windows allow sound into a room and also create a reflective surface from which noise can bounce back into the room. Heavy curtains work best to absorb noise inside and quiet outdoor noises. Thicker fabrics, such as velvet, are optimal; layer curtains for the best results.
Sound echoes off of blank walls, so the more you can break up your room with furniture, wall hangings and textured wall coverings, the less sound will bounce back into the room. Larger rooms are more difficult to control for sound, but well-placed, solid objects will break up sound waves and lower the overall noise levels. The more cluttered your room, the less sound will echo.