Why does my baby make a screeching sound
Sounds that a baby is creating is a manifestation that the baby is active and aware of its environment. Screeching sounds and other types of sound is a form of verbal expression of what they feel.
It's probably because of their age. It also depends on what age they are if you think it's not normal take them to a doctor and see what they think
My kids did that all the time it's there way of talking to you