When do babies start babbling?

Brewster

Seems like Noah was by now (5 mo).  Maren still coos a ton, but no babbling.  Anyone know when babies are typically supposed to be doing this?

4Speedy

I just looked it up in my "Your baby's First Year" book.  It says your baby should begin to babble chains of consonants by the end of the seventh month.  (This is a book by the American Academy of Pediatrics, if you;re wondering about the validity of the source)

Just for reference, my DS is close to 7 months old, he started to babble around 6 months old but so far it's pretty much limited to "Meh-meh-meh-meh" That's the sound he makes when he is frustrated.

Bellisimo

I don't know what the "norm" is but DD's pedi asked at her 4 mo. appt. if she was yet.  She had just started and has since taken off with it.  He asked again at her 6 mo. appt. 

grja

Not sure what the 'norm' is, but dd is babbling now at 4 months. DS was an early talker, so i'm sure she's following in his footsteps.

wellfleet04

Norm is 4-7 months for bababa and by 9 months they should also have D and M sounds.  That said, Kate did not start with Bs until after her 6 month appointment, and only around 8 months did she really babble. She is now far and away the most verbal of all of her friends. Ben is 25 days older than Maren and he's not babbling yet, either.  I am not worried.  Plenty of Kate's IRL friends started babbling closer to 7-9 months.