Great Ideas in Linguistics: Consonants and Vowels

Consonants and vowels are one of the handful of linguistics terms that have managed to escape the cage of academic discourse to make their nest in the popular conciousness. Everyone knows what the difference between a vowel and a consonant is, right? Let’s check super quick. Pick the option below that best describes a vowel:

  • Easy! It’s A, E, I, O, U and sometimes Y.
  • A speech sound produced without constriction of the vocal tract above the glottis.

Everyone got the second one, right? No? Huh, maybe we’re not  on the same page after all.

There’s two problems with the “andsometimesY” definition of vowels. The first is that it’s based on the alphabet and, as I’ve discussed before, English has a serious problem when it comes to mapping sounds onto letters in a predictable way. (It gives you the very false impression that English has six-ish vowels when it really has twice that many.) The second is that isn’t really a good way of modelling what a vowel actually is. If we got a new letter in the alphabet tomorrow, zborp, we’d have no principled way of determining whether it was a vowel or not.

Letter dice d6.JPG
Ah, a new letter is it? Time to get out the old vowelizing dice and re-roll.  “Letter dice d6”. Licensed under CC BY-SA 3.0 via Wikimedia Commons.

But the linguistic definition captures some other useful qualities of vowels as well. Since vowels don’t have a sharp constriction, you get acoustic energy pretty much throughout the entire spectrum. Not all frequencies are created equal, however. In vowels, the shape of the vocal tract creates pockets of more concentrated acoustic energy. We call these “formants” and they’re so stable between repetitions of vowels that they can be used to identify which vowel it is. In fact, that’s what you’re using to distinguish “beat” from “bet” from “bit” when you hear them aloud. They’re also easy to measure, which means that speech technologies rely really heavily on them.

Another quality of vowels is that, since the whole vocal tract has to unkink itself (more or less) they tend to take a while to produce. And that same openness means that not much of the energy produced at the vocal folds is absorbed. In simple terms, this means that vowels tend to be longer and louder than other sounds, i.e. consonants. This creates a neat little one-two where vowels are both easier to produce and hear. As a result, languages tend to prefer to have quite a lot of vowels, and to tack consonants on to them. This tendency shakes out create a robust pattern across languages where you’ll get one or two consonants, then a vowel, then a couple consonants, then a vowel, etc. You’ve probably run across the term linguists use for those little vowel-nuggets: we call them syllables.

If you stick with the “andsometimesY” definition, though, you lose out on including those useful qualities. It may be easier to teach to five-year-olds, but it doesn’t really capture the essential vowelyness of vowels. Fortunately, the linguistics definition does.

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Flap that!

Imagine you’re walking down a sunny street in Chicago and pass by a construction site. Someone yells out, “Adam, the ladder, pick it up!” Congratulations, you’ve just found the elusive wild flap in its natural environment! And not just once, but three times.  Where was it? “Adam, the ladder, pick it up!” Try saying it aloud. If you’re a native speaker of American English, you’ll say all three of the underlined sounds the same way.

Construction worker at Westlake Center, 1988
Come on, Adam, Lulu's having to pick up your slack!

Unless you’re already pretty familiar with linguistics, you’ve probably never heard of the flap (or tap, as some linguists call it), but that doesn’t mean that you’re not already acquainted. In fact, the flap is one of most common sounds of the English language, especially American English. It’s produced by a very quick movement of the tongue against the little ridge of bone just behind your teeth. This video will give you an idea of just how quick:

It’s a little difficult to see, but did you notice that bit in the middle where the tongue suddenly jumped? That was the flap. It’s so fast that it makes the production of most other sounds seem like the proverbial tortoise. A flap takes an average of 20 milliseconds to produce; by contrast, the schwa vowel (it’s an ‘uh’ sound, the most common in the English Language) lasts an average of 64 milliseconds.  You can see why the flap is such a favorite; it’s a huge time saver.

It’s a little difficult to spot a flap  within specialized training because it doesn’t have its own letter, or make any minimal pairs. (A minimal pair is a pair of words that differ by only one sound, like “cat” and “cap”. Because you need to be able to tell the sounds apart in order to tell the words apart, you’re really good at distinguishing the sounds that make minimal pairs, at least in your native language[s]). Usually, it replaces the ‘t’ or ‘d’ sound in the middle of a word, but when you start speaking more quickly, more and more of your ‘t’s and ‘d’s end up coming out as flaps. And that makes sense. When you’re speaking more quickly, you want to be understood, but you just  don’t have as much time to articulate quickly. Since most people will hear the flap as a ‘t’ or a ‘d’, switching one for the other is just easier for everyone.

So that’s the flap, a shy, unassuming sound that you often mistake for one of its more glamorous siblings. Now that you’ve been introduced, though, try to keep an eye out for the little guy. You just might be surprised how often it pops up!