Is it really true that babies have a different sort of cry according to their different needs?

Technically it is true but although I am a sahm and my baby is 7+ months, I can't really tell too - except do for the desperate ones of hungry and sometimes they can calm themselves by suckle their thumb if they need comfort but u are not there immediately. It's true because the tempo and the urgency n pitch of cry is different, and there are 5 common sounds in the babies cries for different physical needs. That's how some of those crying deciphering device works