Unaspirated T’s from the mouth of Babes

This was originally posted on my blog, Notes from a Linguistic Mystic in 2008. See all posts

One of our good friends has a one-year-old little girl, and since she frequently brings her to work, I’ve been able to watch her develop language, and as a linguist, phonetics nerd, and a person, this fascinates me. Recently, she’s been expanding her phonetic inventory (the number of sounds she can make). So, (with her mother’s blessing), I’ve been making a point of listening to the sounds she’s making, and making a number of non-English sounds around her, just to keep her mind open to new things.

Now, a confession: O Human Research Committee, I have a sinned against thee. I’ve been told that any linguistic study with participants under the age of 18 requires around 6 months of Human Research Committee meetings, so listening to the sounds that a baby is making must truly be a cardinal sin. Of that, I am guilty. I beg your pardon, and will duly start pushing papers your way if I every intend to do anything more serious than writing a blog post with the information gathered.

Anyways, today, I was bantering back and forth with the baby and we got into some mimicry (“Can you say Da Da?” “Da Da!”). She’s pretty good with voiced consonants (like B, N, M and D), but I still hadn’t heard her make anything voiceless (like a T, K, or P). Since she’s pretty good with “Da Da”, I started asking if she could say “Ta Ta”, because the only difference between the two sounds is whether your vocal cords (more accurately, vocal folds) are vibrating while your tongue is against the roof of your mouth (try it). At first, she just kept saying “Da Da”, but then, she slowly began to make what sounded to me iike a very a different sound, an Unaspirated T.

This isn’t a sound that most English speakers can distinguish (it’s not a phoneme in English), but it does happen from time to time in certain contexts, like the T in “stick” or “stop”. Most English just hear it as a “D”, and the only reason I can sometimes hear it is because I’ve done a fair amount of training and practice for my various phonetics classes. It’s different from both the English “T” and “D”, but in a very subtle way.

Aspiration 101

This is the part where you get to make fun sounds. Put your fingers on your neck (guys, find your adam’s apple) and say “Ahhhhhhhh”. You’ll feel a vibration. That’s your vocal folds vibrating to give the A its sound. Now, keep your fingers there and say “Dadadadadadadada”. You’ll feel your tongue moving, but the vibration will be pretty constant. Now, try “Tatatatatatatata”. This time, the vibrations will feel like they’re going on an off, off during the T, on during the A. This is because, as I said above, T is a “Voiceless” sound, and D is “voiced”. (If you’re still interested, try the same with “Kakaka” and “Gagaga”, as well as “papapa” and “bababa”).

Now, put your hand in front of your mouth and say “Ta”, then “Da”. Did you feel that puff of air with “Ta”? That burst of air, the momentary delay between the release of the tongue and the start of the voicing, is called aspiration (Wikipedia Link).

Here’s a little hand-drawn graph to help show what the little girl did that astounded me so (click to enlarge):

In the Aspirated T (shown on top) like we have in English “Tap” or “Tip”, the voicing (wavy line) doesn’t really kick in until after the puff of air you felt, so there’s a brief period of time where the tongue is ready to make the A sound, but without the vocal folds vibrating.

In the English D (bottom), like in “Deck” or “Dock”, the voicing is more or less constant, throughout the closure of the tongue.

In the Unaspirated T, the voicing kicks in the moment the T is released, with no delay (or “Voice Onset Time”). That’s why it sounds so much like a D to English speakers, we’re really used to hearing that puff of air.

If you’d like to hear the difference, go to this site featuring the Smalley Phonetics exercises and click 7.13. Listen to the file, keeping in mind that the sounds in the first half labeled Unaspirated are P, T, and K, no matter what they might sound like.

What use would an infant have for a Korean Consonant?

This may seem like a really, really picky distinction. However, it’s actually used in lots of languages. In Korean, for instance, they have different letters for each T/D sound (aspirated, unaspirated, and voiced), as well as for K/G and P/B. Thus, the difference between an unaspirated T and a D could be the difference between two completely different words (like “Cake” and “Bake” in English). Remember, just because we don’t have the distinction in English, doesn’t mean that it’s not important.

So, back to the little girl. It seemed as though she did in fact contrast what I’m pretty sure is an unaspirated T with D (“say TaTa” versus “say DaDa”), and it seems like she really does see the sounds as different. However, this was all lost on her mother (for whom I had to draw the above graph), and who thought that she was just saying “dada” for everything.

The beauty of language acquisition is that eventually, the girl will learn to Aspirate like the rest of the English speakers, and might even forget that she ever could do otherwise. For now, though, I’m going to be watching her voice onset time closely and with great interest.

Maybe I’ll post a followup when her aspiration arrives. If I don’t post anything else, you can just assume that the Human Research Committee got me and banished me to the land of meetings and paperwork. I just hope there’s internet access there…