Your baby will rely to a great extent on his senses inside the uterus (and once he's born) and key development is taking place now.
The ears continue to move up toward their final destination, but your baby can't hear at this stage. Hearing requires the middle and inner ear to structurally mature and the inner ear to complete nerve connections to the brain. Hearing will, however, be one of the first senses to develop and can be tested by seeing if the baby responds to the sound waves that reach him in the uterus. Judging when taste is established is harder, but taste buds have started to appear on the tongue.
Your baby's eyes have a lens and early retina but even if the eyelids were open the eyes would not yet be able to see light signals. The lens is solid and the optic nerve is not yet responding to signals from the retina.
More signs of bodily movement appear but although your baby is quite active he is too light for you to feel the kicks. But you'll be fully aware of him in about two months (see You are 19 Weeks and 3 Days).