Solutions.
1.) Relog
2.)Install SAMP Add on, it fixes shit load of bugs and iirc fixes this too.
Vary Post count btw :^)
On my observation (although I don't guarantee the legitimacy since I have yet to find the cause of this from a official source yet) I think it's not baby crying exactly.
It's your normal ped sounds and vehicle sounds being bugged into one sound and that sound being very high pitched, so whenever you walk on the ground or drive a car the high pitched sound gets used instead and due to repetition of sound (looping sfx) it often giving a baby like crying.
Although I never experienced this in Singleplayer tho,only SAMP servers.