Sound change is the main drive of languages change.
Types and terminology
Sound changes can be arranged in three broad classes: addition, loss and modification, and on the other hand, into conditional and unconditional changes.
Types of additions:
Types of modifications:
- Merger: Two sounds fall together to be pronounced the same. An example is the merger of English /w/ <w> and /ʍ/ <wh> in most dialects.
- If the end result (as is the case of /w/ here) is essentially the same as one of the original phonemes, one may speak of a merger of the other phoneme into the other.
- One might think that any merger must involve such a case, however this isn't the case: sometimes both the original sounds remain, except now as allophones. An example is the merger of */β/ <v> and */b/ <b> as "/b/" in Spanish: the resultant phoneme retains the allophone [β] intervocally, and the allophone [b] initially & after a nasal.
- A "stealth merger" occurs when two former phonemes end up becoming allophones without either of them changing at all, but rather, their environments change. For an example (which has played itself out in many Slavic languages, eg. Russian), suppose a language has the vowels /i ɨ/, and consonants before /i/ are palatalized (eg. /mi/ [mʲi]). Next suppose there are some consonant clusters of the shape /CjV/. If these change to become palatalized consonants as well (so eg. /mja/ → /mʲa/), a result is that palatalized consonants are now separate phonemes. However, if the combination /jɨ/ did not occur in the language, there is also another consequence: /ɨ/ and /i/ are now in complementary distribution, the former only after unpalatalized consonants, the latter only after palatalized consonants. Thus, they've merged. (Cf. palatalization-split.)
- Primary split: A phoneme acquires two distinct allophones in certain environments. This term is usually only used when the distinction, due to later changes in the environment, becomes phonemic.
- Secondary split
- The preposition matters here. A merger with zero may involve epenthesis, in a fashion similar to
- Vowel loss:
- Apocope is the loss of a final vowel.
- Syncope is the loss of a medial vowel.
A sound change may affect the outcome of another change, or the conditions of it.
- If change X applies to a result of change Y, it is said that Y is feeding X. Any case of phoneme drift is a string of several changes feeding one another.
- If change X applies to a phoneme that was previously also in some places affected by change Y (to something that X doesn't affect), Y is said to be counterfeeding X.
- If change X applies in a context § that was previously created by change Y, it is that Y is bleeding X.
- If change X applies in a context § that was previously also in some places affected by change Y (to something that doesn't trigger X), Y is said to counterbleed X.
Neither a feeding or bleeding change is required to completely enable the change it is *eeding (and obviously, a change that is completely counter*ed does not happen at all).
Both conditional and unconditional changes can be (counter)fed, but only conditional changes can be (counter)bled.