Since the 1970s it has been observed that the fetus responds to various sounds in the form of fluctuating heartbeats.
More recent studies have confirmed these findings by detecting new methods of responding to fetal brain centers responding to sound stimuli.
It is known that at about the 20th week of gestation the human fetus can hear and respond to external sounds from the environment and internal sounds from its mother. During the 27 weeks of gestation, acoustic stimuli begin to alter and organize the brain cortex in the area responsible for processing sound.
The immediate acoustic environment of the mother, which is the fetus, is made up of a variety of sound stimuli, which include the sound of her heart, the sound of her breathing and the sound of her voice.
These sounds are a constant and are an important part of the fetal neurodevelopment as they provide a memorable sound base that the baby recognizes.
It is on this basis that the baby learns new sounds and treats the baby.
It has been shown that the sound of the mother’s heart that dominates the endometrial environment is reflected in the fetal memory. That is why the recorded sound of the mother’s heart is recognized by the newborn and works soothing, calming and lulling the baby.
The mechanism of hearing in the human ear can capture sounds with frequencies from 20 to 20,000 Hz, but the fetus is inserted by tissues and amniotic fluid that decrease the intensity of sounds from the outside world.
The high frequencies are reduced by about 20 dB, the low frequencies are slightly reduced. The sounds in the amniotic fluid surrounding the fetus reach it with bone conduction, that is, with pulses transmitted through the bones, because the acoustic drum still does not work. The pressure caused by sound in the amniotic fluid causes oscillation in the fetal skull which is transmitted internally. There it reaches the human hearing mechanism located in the cochlea, which is stimulated by a series of acoustic nerves that cause the brain to hear.
It has been found that the embryo’s response to music exhibits a gradual maturation following its biological age.
Thus, an embryo at 28 to 30 weeks of gestation may respond to music by transiently increasing or decreasing the heart rate associated with music intensity.
But larger embryos than 33: the week of gestation show a more complex reaction with a long-lasting change in heart rate with increased pulse rate and changes in body movements.
It thus appears that the perception and processing of complex sounds is better understood from the 33rd week onwards.
The music seems to have multiple direct and indirect effects on the mother but also on the fetus with beneficial effects.
For the mother, music has a positive effect on her endocrinological system by regulating the secretion of mainly steroid hormones from the adrenals and gonads. It also has a positive effect on stress management and helps promote a sense of joy.
These changes in the pregnant woman contribute positively to the development of the central nervous system of the fetus by promoting axogenesis, synaptogenesis, and nerve cell organization in general, and positively contributing to the future cognitive and cognitive performance of the fetus.
Exposure of the pregnant woman to music also causes positive changes in fetal behavior, changes that follow the baby and after birth.
Studies have shown that the number of nerve cells in the areas of the brain responsible for hearing perception increases in neonates exposed to sounds that have a musical structure, shape, melody and rhythm in the embryonic period, while the same studies have revealed in embryos exposed to sounds without rhythm, melody and more generally musical structure.