Before I begin I want to clarify some linguistic terms. When we talk about sounds in language, we use the term phoneme to mean the smallest unit of sound that can convey meaning. For example, both b and p are English phonemes because "big" and "pig" mean two different things. When we write about phonemes we represent them in slashed lines, such that the phoneme for the sound in "mom" is written as /m/. As I talk about the sounds that Del is using I will use this linguistic convention to make things less confusing for me to write about as her language skills gain complexity. If something needs additional clarification, please let me know in a comment so that I can assure to the best of my abilities that every post I write is accessible to those with no prior knowledge of linguistics. Also, I have not yet been able to figure out how to add subtitles for those of you who are Deaf or HOH (which is not a huge deal right now because Del isn't yet talking!), but that is something I will be looking into and hopefully adding to future videos.
Now, onto babbling! Babbling in English typically starts with bilabial sounds, which are produced by bringing both lips together such as for the sounds /m/ and /b/. These sounds are easy for a baby to make because the lips are fairly large articulators, or parts of the mouth used for creating speech sounds, such as the lips, tongue, alveolar ridge, velum, etc (see diagram above for reference points for the various articulators). Bilabial sounds occur early in babbling development because using them for sounds production doesn't require a great deal of fine motor skill. The bilabial sounds that babies usually babble with first are voiced phonemes /b/ and /m/, which are produced with vocal cords vibration, as opposed to the voiceless phoneme /p/ which is produced without vocal cord vibration. To get a feeling for what this means, put your hand on your throat and hum on an /m/ sound. That vibration you feel is your voice turning on; your vocal cords vibrating. Now keep your hand on your throat and repeat a soft /p/ sound; see, no vibration!
In typical babbling development, /b/ will usually precede /p/ . I believe this is because it's easier for babies to simply turn on their voice for /a/ (all vowel phonemes in English are voiced) and then bring their lips together and apart to create the syllable /ba/, than it is for them to time the vibration of their vocal cords for a voiceless+voiced syllable like /pa/. Babies also tend to alternate early on in babbling between nasal phonemes, or sounds made with air flowing through the nose such as /m/ and /n/, and oral phonemes, or sounds made with air flowing through the mouth such as /b/ and /d/. The reason that nasal and oral phonemes such as /m/ and /b/ are often interchangeably babbled is because these young babies have not yet mastered control of their velum, the soft flap of tissue way at the back of the soft palate that opens and closes the doorway between the oral and nasal cavities. The video posted here demonstrates our baby's (pretty darn adorable) version of this learning curve.
Del started her English babbling experience by exploring bilabial sounds /m/ and /b/ right around five months of age, give or take a week. This video was (luckily!) captured very early in her babbling career, for which I'm grateful because it demonstrates that she's still working on the timing of her breath support and the movement of her velum opening and closing, and is inconsistent with the sounds she creates. She seems to be gearing herself up to make sounds by moving her lips and tongue without any vocalization prior to the babbling. The video was taken about two weeks ago (on September 7th), which any fellow parent can attest is a lifetime in the rapid development of an infant! She is currently babbling more consistently with /b/ and /m/ sounds, and to date has also used the phonemes /n/ (as in "no"), /h/ (as in "hi"), /d/ (as in "dye"), /g/ (as in "guy"), /w/ (as in "why"), /j/ (as in "yes"), and the occasional non-linguistic "raspberry" that babies seem to love making so much! She also frequently squeals, screeches, and growls, delighting in the sheer noise she is able to create. Her vocalizing still occurs, but less frequently now that she has discovered the magical fun of consonants.
Her ASL babbling started around four months with frequent hand waving and finger play. As she grows, her hand movements have become smaller and more precise, with more of the movements occurring within the linguistic signing space in front of her body. She has recently started to experiment more with fine motor skills when hand babbling, and will hold her hands up in front of her face while she's playing quietly by herself and turn them around and make various hand shapes with one or both hands. To date we have seen her make the handshapes for the letters "A," "N," "S," "T," "L," and many of her own invention. She also will hold both hands up and rotate them around each other as if she is signing, "sign." My personal favorite is when she completes some kind of Del-invented hand sign and then holds it up to show us with the widest, most proud smile on her face. Yesterday Daddy F, Del and I were out for breakfast at a local greasy spoon. Del was sitting in her stroller, observing all the lights and lines around us while Daddy F and I chatted and ate our breakfast. There was a man sitting alone in the booth next to us who was exchanging smiles with Del. At one point she held up her hand with fingers spread and palm facing him and waved it a little - a classic wave. Then she made an "L" with her thumb and pointer finger, and pointed right at him, precise as could be! The only way it could have been better is if she had winked at him.
