This accent of the English language isn’t very easy to deal with, and I’m leaving here some notes which would explain how I’m developing my English list.
A very basic analysis shows that English has 10 vowels. But this is not enough, because with just them, diphthongs can’t happen properly. Let me list the vowels using words:
At this point, some may have noticed that “caught” and “cot” may have the same vowel. Which for those people is true indeed. But in some regions, they are still distinguished, making “caught” rhyme with “for”, and “cot” with “far”.
Now, let’s take a look at the diphthongs, which are five:
As I mentioned previously, with just the 10 basic vowels, those diphthongs can’t be recreated, so they need to have symbols for themselves. So this makes now 10 vowels + 5 diphthongs. But it’s not over yet, there is still a problem that may emerge. If the speaker doesn’t distinguish “cot” from “cought”, then, how could “far” and “for” be distinguished? “Far” would not be a problem, but “for” would be. How could it be recreated without the vowel needed for it? maybe using part of the diphthong from “toe”? This wouldn’t sound quite right for some people. So, what now then? Those are two of what are called “rhotic diphthongs”. “Rhotic” is a word that refers to “r” sounds, so those are diphthong with “r” sounds. They are as follows:
Some accents may make the diphthong from “tour” into “or” in some words, but a longer list of example words could suffice to ensure the difference. But the point of all this is to show that those five rhotic diphthongs are needed as well, making up for 10 vowels, 5 diphthongs and 5 rhotic diphthongs. Unfortunately, this is quite big, and gets enormous when combined with the consonants. But this is still not over yet.
There are two vowels which I left uncommented so far, because they’re not very outstanding, and they can usually be replaced by others without causing troubles. So they don’t make up part of the essential phonemes. those are
"a" from about
The first one is the long “ah” vowel, usually it doesn’t have much difference from “cot”, out of the length, and since this is disregarded in singing, it can be left out, at least, for American English. The other vowel is the schwa. It is an unstressed vowel, which orthographically can happen as the five vowels from the alphabet. In simple terms, it is a more closed “uh” sound, and because of the similarity, the schwa can be replaced by such sound. Also, speakers don’t usually distinguish them consciously.
This would technically raise the vowel count to 12, but as mentioned, those last two aren’t strictly essential ,and can be left out.
Most of the exceptions I’ve mentioned here don’t apply for British English, and this makes this accent require about all of them to have the needed distinction between the phonemes.
Unfortunately, this shows that English is not an easy language to deal with, and having 20 sounds related to vowels makes things even more complicated, but it is more difficult to avoid this.