Does an unborn baby know his mother's voice? Psychology professor Anthony DeCasper advised an ingenious experiment to find out. He placed padded earphones over a newborn's ears and gave him a bottle nipple attached to a closed rubber tube. Changes in pressure in the tube switched channels on a tape recorder. If the baby paused extra long between bursts of sucking, he heard on channel if he paused shorter than average, he heard the other. The baby now had the ability, in effect, to change channels. DeCasper found that newborns choose the recording of their mother's voice over that of another woman's. The baby, however, has no innate interest in his father's voice, which is heard in the womb only from time to time, while the mother's voice is ever present. Within two weeks after birth, however, the baby can recognize Dad's voice too. A newborn is even attuned to the cadence and rhythm of his native language. In a French study using a setup similar to DeCasper’s, French babies given the choice between French and Russian words responded more to the sound of French. Brian Satt, a research specialist in clinical psychology, has parents sing a lullaby-like 'womb song' to their babies. The unborn baby often develops a specific, consistent movement pattern when its song is sung. According to Satt, most parents can calm a fussy newborn with the song most of the time, which is a prize worth more than rubies to a new parent. He is roused by a heavy jolt. His mother has tripped and fallen heavily on one hip. He is much too well cushioned to experience any injury, but her pain and the fear that she may have hurt him floods both their bodies with adrenaline and other stress-related hormones. He cries and kicks vigorously, a cry never heard because there is no air to make sound. As she recovers the stress hormones ebb away, and he calms down too. Which of the following is NOT mentioned about the unborn baby in the passage.'?