1089: Unstable Vowels Dec 2, 2017

'Do', 'does', and 'don't' are obviously related to each other, as the latter two forms are only versions of the first. Nevertheless, each one of them has a different vowel; in Standard American English, the vowel is 'do' is [u], in 'does' it is [ʊ], and in 'don't' it is [oʊ̯]. You can see these on the chart (which is modelled after where a tongue has to move to pronounce the vowel) from speechmodification.com below. These vowels are said to be unstable, and 'do' is not the only word to have this unstable vowel historically, but it is a good example of how these tend to lengthen and lower (see chart and observe that [ʊ] is produced physically lower than [u]). Some of the reason for this is that it can be easier to produce, but in some languages, vowels will change regularly depending upon which consonants potentially follow them; this concept will be explored in the future soon.