My oldest son rarely babbled. He hardly spoke until he was around 2 years, 6 months. He just didn't have the desire for reciprocal interaction. Even as an infant to toddler, he was more interested in objects and how things worked. He did have a few times where he babbled but not much.
An example a babble when he was older ....... I will never forget when Nate was a little over a year old. Usually this "babble" occured when we were driving. We often heard him say in a high pitched voice "la la da la la la da da...." It was a pretty large sequence. He would follow that up in a low pitched voice with a "bla bla". Very brief. That was then followed by the higher pitched babbling voice that went on for a much longer time. I will never forget when my husband started laughing.
He said, "Just listen to what he is doing. Listen carefully". He then told me that Nate was mimicking our conversations. My husband doesn't talk a lot compared to me. He was the low voice with few babbles and I was the high voice with many LOL
They completely pay attention despite the babbling LOL.
My son was speech/language delayed, especially in articulation and expressive language. He didn't babble so ended up having a little more difficulties than other kids with forming words - he didn't get the practice (my theory). With his expressive language skills, he just didn't have the interest. We were concered that he would never talk. He talks nonstop and has a great vocabulary!!