At the stage of "variegated babbling", babies vocally babble constonant-vowel-constonant (CVC). From this stage, babies develop toward their first words. Likewise, babies of ASL-speaking families also babble with some more varied patterns during this stage.
Variegated babbling began to emerge in Juli at the end of 8 months (m8w5) -- a combination of two different syllables or different patterns. E.g. she manually babbled more variegated, especially the "s-a-e" sequence. She also waved with her index finger sideway.
Video: variegated babbling both manually and vocally.
Juli babbled a certain sequence that contained a closed-hand string of the handshapes "s", "a", and "e" in a loop. It was difficult to capture the moments of this sequence (until later).
A week or two later (m9w2), in addition to the usual work-like syllable (in which the dominant hand clapped onto the non-moving base hand), she also manually babbled some new syllabic babbles: clasped hands move up and down repeatedly, and a milk-like movement (opening and closing hand repeatedly, palm orientation up).
Video clip: Juli produced variegated babbling while watching Ben Bahan's The Ball. Unfortunately, I had to interrupt her distinct babbling while I grabbed a camera and only captured the small part.
Video clip: For the past months, I asked "more or finish?" When Juli responded, these ASL words more and finish were within about the same space.
For a little experiment, I decided to use them in different space to distinguish one from another. I showed her the signed word finish/done above the mid-level signing area.
Sure enough, Juli did raise her hands while babbling "done".
Then in the next week (m9w2), Juli babbled a lot both vocally and manually. She vocally babbled "bwa- bwa", "papa", and "dada". Then next week (m9w4), she vocally babbled more variegated -- "aba", "baby", "mama", "mom", "dada" and so on.
Juli waved bye-bye somehow more distinctly one evening when I left for work.
It appears that syllabic babbling begins with the whole hands (gross motor) and then gradually narrows down to the fingers (finer motor) of babbling during this variegated stage.
For the last couple of weeks or so, I fingerspelled #art (fingerspelled loan) to Juli every time she looked at the artworks.
I pointed to the artwork and fingerspelled #art within the visual field. My hand moved to the next artwork and repeated the fingerspelled word #art.
This week (m10w2) I noticed the manual alphabetical letter "T" among the finger babbles that Juli produced frequently.
One late evening at the dinner, I showed Juli by pointing to the kitchen light which was on and articulated light cl-on. Then, I pointed to the other light which was off and articulated cl-off. Juli responded by imitating on-off-on-off.
A few moments later, Juli started babbling "sae" syllables. I responded to her by imitating her.
Then, Juli and I babbled turn-taking with two different syllablic babbles: the syllable cl-light-on/off and the "sae" syllable.
Now that Juli could manually babble the "sae" syllable. I figured out that she could possibly get close to the syllable similar to the form of a-r-t.
I fingerspelled #art. Juli did somehow imitate it. First, I caught one of the handshapes which was the manual letter t. Second, it didn't look like the "sae" syllable.
. Video clip: As I was multitasking, I was surprised when Juli leaned forward. Then she tapped on my waist to get my attention when she wanted more.
With the camera ready, I was pretending doing the same task. Again, Juli leaned forward and tapped on my waist and even tugged my shirt.
Juli quietly watched out the window, sitting on my lap. She formed an ILY handshape (which is the abbreviation for "I love you").
Whether it was just a coincidence or she formed it subconsciouly, it was a lovely sighting. It is one of my most favorite images.
More than few months ago, Dude waved "ILY" as he was about to leave for work. Juli's hand formed the ILY handshape momentarily. It was difficult to say whether she acquired it consciously or subconsciouly. Or, it could be just a pure coincidence.
Also see canonical babbling in sign language.