American English Phonetics

6. The vowels of GA

Vowels are difficult to describe in that, unlike consonants, it’s impossible to give an exact position of the speech organs.

For example, the bilabial plosive /p/ is produced by first bringing the lips together (bilabial) to form a complete closure, air pressure is built up behind the lips and then released (plosive). But, if there was a space between the lips (so that air could pass through) during the production of the sound, we would be talking about a fricative and not a plosive anymore.

The point is that a consonant can be a stop or a fricative but not somewhere in between. This is possible, however, when describing vowels.

For example, we can say that to produce /uː/ you arch the back of your tongue toward the soft palate, close but not touching. But for /ʊ/ you do the same, except that the tongue is not as close to the palate as it is for /uː/.

That is to say, the boundaries between vowels are not absolute; rather, they’re on a continuum.