In phonology, a chain shift is a phenomenon in which several sounds move stepwise along a phonetic scale. The sounds involved in a chain shift can be ordered into a "chain" in such a way that, after the change is complete, each phoneme ends up sounding like what the phoneme before it in the chain sounded like before the change. The rules making up a chain shift are said to be in counterfeeding order.
For example, if in some language the three vowel phonemes /æ ɛ e/ undergo a change so they became respectively /ɛ e i/, those three changes would constitute a chain shift and could be summarized as
- æ → ɛ → e → i
A drag chain or pull chain is a chain shift in which the phoneme at the "leading" edge of the chain changes first. In this example, the chain shift would be a pull chain if /e/ changed to /i/ first, opening up a space at the position of [e] which /ɛ/ then moved to fill. A push chain is a chain shift in which the phoneme at the "end" of the chain moves first: in this example, if /æ/ moved toward [ɛ], creating a "crowding" effect and causing /ɛ/ to move toward [e], and so forth.
- (aː →) æː → eː → iː (→ əi) → ai and (ɑu →) ɔː → oː → uː (→ əu) → au
A chain shift may affect only one regional dialect of a language, or it may begin in a particular regional dialect and then expand beyond the region in which it originated. A number of recent regional chain shifts have occurred in English. Perhaps the most well-known is the Northern Cities Vowel Shift, which is largely confined to the "Inland North" region of the United States. Other examples in North America are the California vowel shift, Southern vowel shift (in the Southern United States) and the Canadian Shift. In England, the Cockney vowel shift among working-class Londoners is familiar from its prominence in plays such as George Bernard Shaw's Pygmalion (and the related musical My Fair Lady):
- iː → ei → ai → ɔi → oi
Many chain shifts are vowel shifts, because many sets of vowels are naturally arranged on a multi-value scale (e.g. vowel height or frontness). However, chain shifts can also occur in consonants. A famous example of such a shift is the well-known First Germanic Sound Shift or Grimm's Law, in which the Proto-Indo-European voiceless stop consonants became fricatives, the plain voiced stops became voiceless, and the breathy voiced stops became plain voiced:
- bʱ → b → p → f
- dʱ → d → t → θ
- ɡʱ → ɡ → k → h,x
- d → t → ts,s
- (ɡ →) k → kx,x
- (b →) p → pf,f
The Romance languages to the north and west of central Italy (e.g. French, Spanish, Portuguese, Catalan and various northern Italian languages) are known for a set of chain shifts collectively termed lenition, which affected stop consonants between vowels:
- pp → p → b → β,v
- tt → t → d → ð (or vanishes)
- kk → k → ɡ → ɣ,j (or vanishes)
In this case, each sound became weaker (or more "lenited").
It is also possible for chain shifts to occur synchronically, within the phonology of a language as it exists at a single point in time.
Examples (Guthrie 1968) follow:
Underlying form Chain-shifted form sal "to work" sal-i → sɛli βɛɛd "to give" βɛɛd-i → βeedi bet "to carry" bet-i → biti bis "to refuse" bis-i → bisi kolən "to go down" kolən-i → kulini tɔɔd "to arrive" tɔɔd-i → toodi suɛm "to hide oneself" suɛm-i → suemi
Another example of a chain from Bedouin Hijazi Arabic involves vowel raising and deletion:
In nonfinal open syllables, /a/ raises to /i/ while /i/ in the same position is deleted.
The contour tones are lowered to a lower tone, and the lowest tone (21) circles back to the highest tone (53).
Synchronic chain shifts are an example of the theoretical problem of phonological opacity. Although easily accounted for in a derivational rule-based phonology, its analysis in standard parallel Optimality Theory is problematic.
- Guthrie, Malcolm. (1968). Notes on Nzebi (Gabon). Journal of African Languages, 7,101-129.
- Kirchner, Robert. (1996). Synchronic chain shifts in Optimality Theory. Linguistic Inquiry, 27, 341-350.