At Baltimore's St. Agnes Hospital, classical music was provided in the critical-care units. Half an hour of music produced the same effect as ten milligrams of Valium, says Dr. Raymond Bahr, head of the coronary-care unit. Some studies show it can lower blood pressure, basal-metabolism and respiration rates, thus lessening physiological responses to stress. S-IgA speeds healing, reduces the danger of infections, and controls the heart rate.
Studies indicate both hemispheres of the brain are involved in processing music.
You will notice that nowhere in these two paragraphs appears any mention of rock music and its effects on the unborn. The amniotic fluid along with several layers tissue in a mother's womb would definitely be a very effective sonic damper - protecting the unborn child from damaging sound levels even in the loudest of rock concerts. My daughter was exposed to Christian rock in the womb. She doesn't have any stress and can cope perfectly well with the world. Even if it costs me a little sleep and aggravation, I would prefer her to be alert and learning with a keen intellect at all times, not drugged into submission.