This music s released. Hatsune Miku include a version that sings to the voice of a child from the past.
Please listen to it!
Apple Music
https://music.apple.com/jp/artist/%E3%82%B1%E3%82%A2%E3%83 %87%E3%82%B6%E3%82%A4%E3%83%B3/1003659604
YouTube
https://youtu.be/_TaSvYvFBaM
Since the sound heard in the womb is water conduction, the baby is born in a state where the high frequency band can be heard well. After that, the auditory filter changes to focus on the frequency range of the human voice, so you can hear the human voice even in the background noise. In the case of hearing-sensitive children, training to focus on human voices will reduce noise.
How hearing-sensitive children hear
At the 20th week in the womb, only the eyeballs and ear holes are formed. From about 6 months after fertilization, the baby also hears the sounds that the mother hears. Children whose mothers often listen to music after birth seem to like music and hum at the same pitch as the music they hear. People sing without being taught.
