Sound can be heard by an infant in the mother’s womb by the middle of the second trimester of pregnancy. This is the point at which the baby and mother start to connect emotionally because the baby can recognize the sound of the mother’s voice. Experts say that from the second trimester onward, mothers can converse with the baby and even sing to him or her because the ears and organs responsible for detecting sound are almost fully formed. In the last trimester, mothers can actually perform sound experiments on the unborn baby, such as walking into a room with loud music from one that is silent. The sound of the loud music will startle the baby, and the mother will feel the baby’s jerks and movements. Patting the belly lightly also generates sound waves that the baby will respond to with slight movements or body stretching.