To Seek Out New Vowels ...

Part of my teaching this semester (with my colleague Alice Turk) involves an exploration of space: the space of the remarkable array of speech sounds humans can produce. Consider just the vowel space, for example. Phoneticians map the infinite space of possible vowel qualities by reference to a set of reference points at the edge of vowel space: the final frontier. They’re known as the primary cardinal vowels.

The Primary Cardinal Vowels

When you say Cardinal 1, your tongue is pushed so high and far forward that if you pushed it any further the airstream squeezing out past your tongue and teeth would create audible friction.

When you say Cardinal 5, the doctor should hardly need the tongue depressor. And Cardinal 8 is not just “Ooh!"; it’s the oohiest ooh you can ooh, with your lips so rounded that a pencil would barely fit in the hole. And by definition, adjacent cardinal vowels are auditorily equidistant: [e] (Cardinal 2) should sound just as far from [i] (Cardinal 1) as [ɛ] is from [e]; [a] should differ to the ear from [ɛ] to the same degree that [ɛ] differs from [e]; and so on.

For Cardinals 1 through 5 you don’t round your lips, but for 6 through 8 they should be increasingly rounded. The jaw is progressively more open

for Cardinals 1 through 4, and for Cardinals 8 through 5. (Actually all this talk of jaw and tongue positions turns out to be merely a surrogate for an underlying acoustic reality, suggested by the more detailed map on the left, but I can’t cover that here. I’ll talk as if it’s all about tongue positions — a heuristically useful fiction containing more than a grain of truth.)

Vowels fairly similar to the eight primary cardinal vowels are commonplace — like oxygen, silicon, aluminum, iron, magnesium, calcium, sodium, and potassium on our planet.

But there are less frequent vowels too — the rare earth elements of the vocalosphere. The secondary cardinal vowels have the same abstract positions as the primary ones, but the opposite lip rounding:

The Secondary Cardinal Vowels

YouTube has videos for everything, the cardinal vowels included. Here, for example, you can see an animated vowel quadrilateral with audio of the famous phonetician Daniel Jones (1881–1967) pronouncing all of the cardinal vowels in a quavery monotone.

Some secondary cardinals are not easy to encounter viva voce. Scottish Gaelic is quite unusual in having the extremely rare Cardinal 15 as well as the fairly unusual Cardinal 16.

Cardinal 12 is more like technetium than the rare earths — it virtually doesn’t occur in nature at all. It’s basically an [a] with lip rounding, but rounding your lips while maintaining a wide open jaw position and tongue low at the front is a struggle. Hardly any self-respecting languages use Cardinal 12 (though Danish comes close).

This has still only scratched the surface. Many languages have more than 18 vowels. English has around 20 vowels (dialects differ), Cambodian has more than 30, and some languages have even more than that. How so?

First, various additional vowel sounds populate the interior of the vowel-space quadrilateral. (One is [ə], heard in the first and third syllables of banana. Others include the vowels of English pit and put.)

Second, many languages have diphthongs — vowel sounds that slide from one point to another in vowel space.

Third, vowels can differ in other features than mere position in the vowel-quality quadrilateral:

• nasal air flow (French has four nasal vowels);
• duration (Dinka, in South Sudan, uses three different vowel lengths);
• breathiness (Dinka also has breathy-voiced vowels);
• constriction in the pharynx;
• creakiness (“vocal fry”); and (very rarely, in certain languages of southwestern Africa)
• epiglottal stridency.

(And I’m completely ignoring tone.)

I always enjoy teaching this stuff. The variety is amazing, the physiology is complex, the physics is fascinating. And as a practically useful introduction to one aspect of human linguistic diversity, it’s a wonderful subject for an undergraduate course.