Originally Posted by A. G. Maisey
Mercenary:- I believe that you will find the unwritten vowels to which you refer are certainly non-existent in script, but exist only in speech, where they are identified as "allophones". In other words, the vowels do not exist, they only appear to exist because of pronunciation.
An allophone is a variation of the phoneme, and this variation can be inconsistent, varying from geographic location to geographic location, and forming a contributing factor to regional accents, it can even vary from person to person where it can assist in identifying an individual speaker.
This occurs in all languages.
(a phoneme is a unit of sound in a particular language; an allophone is a variation of a spoken phoneme)
My apologies for the pedantry, but my post #9 was the short version of a 20 minute lecture.