This probably happened after the original Old Aramaic phonemes disappeared in the 7th century BCE, and most likely occurred after the loss of Hebrew c . 200 BCE . It is known to have occurred in Hebrew by the 2nd century CE . After a certain point this alternation became contrastive in word-medial and final position ( though bearing low functional load ), but in word-initial position they remained allophonic.
22.
This is why the distinction between close and near-close vowels is phonemic, even though the contrast has a low functional load, with only very few actual minimal pairs such as ('rider', shortened vowel ) vs . ('knight', originally short vowel ) or ('door', lengthened vowel ) vs . ('to increase in price', originally long vowel ).
