Vowel Breaking Sound Change

Question

I find breaking to be an interesting sound change which I haven't used much before, and I'm trying to figure out when it would most commonly occur. My understanding is that it would be prone to happen if the vowel is a front vowel and the consonant or consonant cluster is pronounced in the back of the mouth, like "kald" becoming "ċeald" in Old English. Similarly with "ċealf", "hīeran" and so on.

Now I think this sound change is a bit daunting to keep in mind when going over how certain words might change from a proto-language to a current language, so I had in mind creating a kind of cheat sheet showing which vowels might break into which diphthongs. I'm also looking to find good examples of vowels breaking in other languages.

I'm aware of a notable example, Proto-Germanic "ek" turning into Old Norse "jak", which turned into the modern word for the pronoun "I" in several Scandinavian languages. Something similar happened with "hertōn" turning into "hjarta".

Keeping this sound change in mind, I think of a potential word "ahel" in a proto-language and turn it into "ajal" or "aial" or "ajel" in the descendant language.

I found some good examples too in Romanian, such as Latin "pellis" turning into "piele", meaning "skin", and "porta" into "poartă", "flōr" into "floare", "petra" into "pietră".

In Rejang there are three specific vowels breaking, "ə" turning into "êa", "i" turning into "ea", and "u" turning into "oa", such as in "tənur" turning into "tənoar" turning into "tênoa", meaning "egg".

It seems to me that if the breaking vowel is "e" or "a" there seems to very often be an addition of an "i" or "j" sound, while "u" or "o" tends to have an "a" put after it, and the consonants that tend to trigger this kind of change are "r" and "l" mostly. Of course, this is just my guess having looked at some examples of vowel breaking, and I would like to find more examples.

Answer 1

"Breaking" tends to involve a vowel becoming a diphthong, which requires more articulatory effort but makes it more perceptually distinct. This can either result in a diphthong "centered" on the original position—for example, e becomes aj—or it can involve inserting a different sound at one end or the other (like i becoming aj).

Off the top of my head, the latter is more common. We see that happening in Old English vowel breaking, for example (æ > æə > æɑ), and also in Modern English's Great Vowel Shift (u > əu > au). Old English vowel breaking was triggered by consonants at the back of the mouth, but the Great Vowel Shift was triggered by the vowel space getting too crowded, and the high vowels needing some way to become more distinct. Crowdedness also led to breaking in the Western Romance languages, as in Latin fokum > Spanish fwego (via an intermediate *fwogo), Latin festam > Spanish fjesta.