Canonical (reduplicated) babbling is usually identified with the onset of babbling at around 6-7 months. It consists of reduplicated syllables (i.e. "babababa").
To distinguish canonical babbling (e.g. "bababa") from the earlier marginal babbling (e.g. "ba"), canonical babbling includes syllables in a timing relationship that conforms to mature language restrictions.
The onset of the stage is relatively sudden, and many of these units are reduplicated (e.g. "bababa" and "dadada" in speech or "closing-opening-hand" and "batting-up-down" in signing).
By the end of 7 months old, Juli had babbled manually and vocally much more often, especially with the syllabic pattern of the ASL word "work".
Ever since the first evening I was out for work (teaching ASL), I showed Juli my black workbag to create an association of my long-hours absence with work. I explained to Juli mother drive, go-to work now. mother ix-me will-be home.
The ASL word work had been one of the most frequently used words in the past weeks. Dude went to work -- father go-to work. [bye-bye]. He came back home -- father work done/finish, now home! and such.
Videoclip: As I was preparing for work another evening, Grandma Z held Juli in arm and explained mother will go-to work. ix-she will come-back. (The first frame of the video showed "work" as I began videotaping a bit late.)
Then Juli babbled, imitating what Grandma Z signed. Among the babbles, one stood out distinctly was the ASL word work.
As I was about to leave, I explained to her again including the word work. Juli was babbling "work".
That is, Juli picked up the pattern from our language and produced her first babble based on the pattern of the ASL word, "work".
Juli still babbled in the ASL form of "work". A few other babbles had also emerged that week or before.
A month later (m8w4), Juli's paternal relative, who lived out of state, wanted to adopt the dog we temporarily called "Deputy". He asked that we picked him up at SPCA. For the next half week, we had to look after him till the dog's flight date.
As a result, the ASL word #dog and/or the simplified old sign "patting-on-leg" were the most frequently used that week.
Before Deputy flew for his new home, Juli had been babbling the patterned units of the older ASL sign. Juli was patting on her leg.
The day before Deputy departed, Juli woke up one morning. As soon as she sat up herself, she patted on her thigh so distinctively.
Juli vocalized "mama" or sometimes whimpered "mmmm" usually when she looked for me in my office when I was out for work.
One day (or night) that week, when I came back home from work, Juli reached out her arms excitedly and vocalized "mamama".
The second time I returned home from work, Juli again reached out her arm and mouthed "mamamama".
In ASL linguistics, the Symmetry Condition (Battison) states that, if both hands in a two-handed signed word move, then the handshape must be the same and the movement is either alternating or simultaneous. E.g. bath, maybe, etc.
On the other hand, the Dominance Condition states that, if the hand has a different handshape in a two-handed sign, then only the dominant or active hand can move while the base hand remains stationary (not moving). E.g. enough, cookie.
And so on. There are further if-then rules.
For right-handed signers, the right hand is the active or dominant hand, while the left hand is the passive or base hand. The opposite is true for left-handed signers.
It is a natural rule that governs the structure of signed language. Native signers didn't consciously create this rule.
It is interesting to observe that Juli had been babbling with one active hand onto the base hand, exactly the same as WORK.
Video: "The linguistic genius of babies" by Patricia Kuhl at TED Talk.
What does preserving a language really means? Record it and preserve it in archival? No. Teach a language to others? No.
To truly preserve a language is to speak (manually or vocally, depending on which language it is) to babies in a native environment, as shown an example in the video: a mother (one of 800 people in the world) speaks Koro to her baby.
Why? It has to do with your brain -- the critical period from birth to age seven.
A study shows that at 6-8 month old babies don't discriminate sounds of different language, but in an amazing short time, at 10-12 month old babies turn head to sounds of a language of their own culture. It is a 2 month critical period. They are absorbing certain sounds of the language and shaping in their brain.
Researchers compare each component of nonreferential babbles with the phonetic inventory of an adult signlan. Yonekawa (1984) suggested the number of primes in each parameter such as handshape, movement and location. In a participant, 29% of handshape, and 54% of movement inventory in adult JSL were used in non0referential gestures. discuss that nonreferential babbles with the phonetic inventory of adult JSL.
Petitto and Marentette (1991) showed that 32% of the handshape and 54% of the movement that made up the phonetic inventory of adult ASL were observed in manual babbling. These nonreferential gestures are produced before the onset of signed words.
Native-signlan people who are Deaf (with a capital letter of "D") around the world are truly living preservers, ranging from accurate sign production (or "pronunication") to pragmatics (contexts and discourse styles).
Also see variegated babbling in sign language.