FETAL HEARING

HEARING IN THE WOMB

Why does a baby feel comforted by her mother’s voice or  soothed by the sound of her mother’s heartbeat?  The sense of hearing develops quite early in the womb. As sound penetrates the wall of the mother’s abdomen which surrounds baby, this sense has the chance to develop quite a bit before birth.  By the early age of six months of fetal development, baby is able to respond to sounds.  And with each passing week, baby hears an increased range of both volume and frequencies.  At birth, baby has 12 weeks experience hearing a variety of sounds from both the internal world of the mother’s body and the external environment into which it emerges.

When my friend Erin was pregnant with her son Jasper, I remember her telling me how much he moved when her tea kettle boiled water.  This particular kettle had a lower-pitched choo-choo train whistle that her unborn son could hear.   Later in her pregnancy the family vacationed in Yosemite and Jasper had the same reaction to the sound of the waterfalls. “Whoosh!,” she described the action in her belly as he responded to the thundering sound of crashing water.  These sounds fit right into the categories of what qualities and types of sound a fetus hears.  Research conducted on women in the first stage of labor has taught us what sounds cross the abdominal wall and introduce baby to their sonic future.

TYPES OF SOUND A FETUS HEARS

1. Mother’s Voice (baby hears mothers voices louder than others because it does not need to penetrate the wall of the womb)
2. Bodily Sounds of the Mother (i.e., heartbeat, blood flowing, stomach gurgling)
3. External Sounds from the Environment (i.e., music, voices, trains, planes, waterfalls)

QUALITIES OF THE SOUND A FETUS HEARS

1. Mid-Low Pitch
2. Loud Volume (louder than normal conversation, but too loud is damaging to hearing)

In 1980, the journal Science presented a study on newborns.  Pregnant women read their unborn child a passage from Dr. Seuss’ To Think That I Saw It on Mulberry Street.   They read the passage several times.  After birth, the newborns were outfitted with nipples which controlled what they heard.  They could change the sound of the voice simply through their sucking, one of their earliest voluntary actions. They were listening to a recording of various women reading the Dr. Seuss passage, and one of the women was the mother of the baby.  This study found that newborns preferred to listen to the voice of the voice of the mother.

BABIES, SOUND AND MOVEMENT

How does this research on sound influence learning movement?  Since hearing is more developed than sight, use the sound of your voice to reassure the baby when learning new skills, choose toys and rattles with sounds to guide them in the process of seeing and playing with objects, recall what “familiar” in-utero sounds may be comforting, and, most importantly, SING as a method of play.