In Lesson 20 there was a table of long and short vowels, with quite a few gaps in the "short vowel" column. This is because back in the Sukhothai period the language only had long and short forms for /a/, /i/, /u/ and /ʉ/. Subsequently it was necessary to devise a way of representing short forms of /e/, /ɛ/, /ə́/, /o/ and /ɔ/. Two different solutions were created: one for open syllables (i.e. those ending with a vowel sound) and one for closed syllables (ending with a consonant).
In this lesson we'll only consider open syllables.
The solution for open syllables was to add ะ to the syllable. Here are some examples:
Here are some common words to practise reading.
But what about /ɔ/? You might expect it to be written อะ, but no. The short form of /ɔɔ/ (อ) is written as if it were the short form of /ao/ (เ−า). For example, เพราะ (because) is pronounced /phrɔ́/.
Try reading these words:
ะ is also used to shorten some diphthongs, specifically เ◌ียะ /ia/, เ◌ือะ /ʉa/, and ◌ัวะ /ua/. (Note that the transliteration scheme used isn't able to represent these diphthongs as short.) All three are very rare and are used to represent words in Thai dialect (e.g. เขียะ, /khǐa/, a north western dialect name for a species of cactus), a few imported words (e.g. เปาะเปี๊ยะ, pɔ̀ʔpíaʔ, spring roll) and to represent sounds (e.g. ผัวะ, phùa, the sound made by whipping or slapping). They aren't covered further in this course.