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4.6 Phonological change

Phonetic change

What do you think would be the consequences if, for some reason, the phoneme /i/ in English started to become more and more similar to the phoneme /ɪ/? Think in terms of what this would mean for the Hearer. How might the English phonological system deal with such a change?

One way the pronunciation of a language can change over time involves changes in how particular phonemes are pronounced but not in the number of phonemes. As with other language change, it is usually not clear how the change begins, but the prototypical phone for some phoneme starts to move. In the simplest case, this is all that happens. For example, about 150 years ago the vowel /o/ in some dialects of English, already a diphthong, began to shift so that its beginning was more central and less rounded, resulting in the characteristic [əʊ] of today's Received Pronunciation.

More often a change in one phoneme affects others. This is because the change may either make that phoneme more similar to another or open up a region in the phonetic space where there is no phone. In the former case, the changing phoneme may "push" another phoneme away as it comes close to it. In the latter case, the changing phoneme may "pull" another phoneme into the region where it used to be. Both kinds of changes favor the Hearer because they keep the phonemes as far apart as possible. These processes are best known from the history of vowel systems. The vowels of English have undergone several such changes and in some English dialects are undergoing them now.wikipedia

Sometimes a whole set of vowels will shift in the history of a language.

Probably the most famous example of such a set of changes is the Great Vowel Shift of Middle English. I won't go into it in detail, but what happened was that the pronunciation of all of the tense (long) vowels of English changed, in some cases quite dramatically. For example, the vowel in words such as fine had been pronounced [i]; eventually it became the [ay] of Modern English.

Instead we'll look in detail at some changes going on in the vowels of one English dialect today. A quite striking set of changes is happening in some cities of the Northeast and the Midwest in the US (for example, Rochester, Cleveland, Detroit, Chicago, and Milwaukee). This is called the Northern Cities Vowel Shift; in its most extreme cases, it applies to the set of all of the English lax (short) vowels except for /ʊ/. You can read more about the Northern Cities Vowel Shift in this paper. The figure below diagrams the changes.

Northern Cities shift

As a result of the Northern Cities Vowel Shift, some words in Chicago sound like different words in Indianapolis.

The diagram shows what is happening in vowel space (front vowels on the left). Each arrow indicates the direction of change for one phoneme. The phoneme label and example word appear in the position where the vowel started, that is, its position in General American. The end of each arrow shows where the vowel ends up in the cases where the shift has progressed the furthest. For example, the word cot following the shift is pronounced something like the word cat in General American. The order of the changes is indicated by the numbers. Different speakers, and to some extent different cities, can be seen as being currently at different points within the set of changes. For examples, for some speakers, only changes 1 and 2 might have taken place, whereas for others all of the changes might have taken place. There is also considerable variation, so we should not expect everybody in the Northern Cities to follow exactly this pattern.

The first change to happen was a movement of the /æ/ vowel higher. (Incidentally a similar change has happened in other accents of the US Northeast, but it is normally confined to only some contexts, for example, in glad but not back.) As the vowel moved higher, it also tended to become a front-to-central diphthong. The diagram shows the most extreme change; more moderate changes occurred within the speech of many speakers. Note that once /æ/ has shifted like this, it is the same phoneme as it was in the sense that it is still distinguished from all of the other vowel phonemes in this English dialect and is still used for the same set of words as before (back, glass, fancy, etc.). But phonetically it is no longer [æ], so we could choose to represent the phoneme with a different symbol. Keeping the symbol the same, however, reminds us how this phoneme corresponds to the /æ/ of other dialects.

Apparently the next change to take place was the movement of /ɑ/ forward. This is an example of a "pulling" change; the movement of /æ/ left a gap in the vowel space that /ɑ/ moved to fill so that the vowels remained roughly equally spaced. Again for most speakers the change was not as dramatic as shown in the figure; for many the vowel is closer to [a] (a low central vowel) than to [æ].

The next change to take place seems to have been the movement of /ɔ/ downward. As you'll see in the section on English accents, this change has happened for many North American speakers, but in other accents, the /ɔ/ and /ɑ/ vowels are no longer distinguished. In the Northern Cities, the two vowels remain distinct, and the movement of /ɔ/ can be seen as another example of a "pulling" change since the movement of /ɑ/ opened up a place for /ɔ/.

Next the vowel /ɛ/ became more central. Again this is an example of a change that seems to be occurring more generally in North America, though apparently only in some contexts, for example, in the word level. In the Northern Cities accent, it was probably a response to the rising /æ/ As this vowel became higher, it came to resemble /ɛ/, and there was the potential for confusion since many words in English are distinguished by the distinction between /æ/ and /ɛ/ (for example, bat and bet). As a result, /ɛ/ shifted so that it would be more distinct. This is an example of a "pushing" change; the /æ/ pushed the /ɛ/ into another region of the vowel space.

Next /ʌ/ became more back. This can be seen as both a pulling and a pushing change, pushing because /ɛ/ became more confusable with /ʌ/ as it moved back, and pulling because /ɔ/ opened up a gap in the vowel space when it moved down.

Finally /ɪ/ also moved back. This is an example of a pushing relationship. As /æ/ rose, for some speakers it seems to have reached the point where it became potentially confusable with /ɪ/, and /ɪ/ moved back to make room for it. This is also a change that seems to happening more generally in North America, though again apparently only in some contexts, for example, in the word liver.

Change in some contexts

Allophones often emerge in the history of a language.

Another possibility is that a phoneme will come to be pronounced differently in some contexts but not others. In other words, the realization rules for that phoneme change. Often the changes are examples of assimilation. Here are some examples from the history of English.

Old English /k/ before /i/
In Early Old English /k/ came to be palatalized when it occurred before /i/; that is, the point of articulation moved forward from the velar to the palatal region. This is an example of anticipatory assimilation; the /k/ changes to be more like the /i/, for which the high tongue position is near the palatal place of articulation. Eventually /k/ in this context became similar to [č], that is, an alveopalatal affricate.
Final unstressed vowels
At several times in the history of English, final unstressed vowels have been dropped. In Old English, which had no /ə/ phoneme, there were many words such as /'sʊnʊ/ 'son' with final unstressed vowels that are quite unlike unstressed vowels in Modern English. At some point, unstressed vowels in words such as these became reduced to /ə/, and later this vowel when it was final ceased to be pronounced altogether. This is the reason English has so many "silent e's"; the orthography has been conservative and fails to represent all of the phonological changes.

Phoneme loss

A further possibility is that two phonemes will merge as a result of change in one or the other or both. Obviously this can only happen when the difference between the two phonemes is not so significant in the language, that is, when the phonemes do not distinguish many words. In the section on English accents, we'll see several examples of this. In many North American dialects, for example, the vowels /ɔ/ and /ɑ/ have merged in recent years. This does not create a serious problem for the Hearer because there are not many minimal pairs such as awed/odd and caught/cot that are distinguished only by these phonemes.

Phoneme creation

We saw in the last section how phonemes could be lost. Given what you know about allophones, how might the opposite process take place? That is, how might allophones of the same phoneme (for example, [t] and [th] in English) turn into separate phonemes?

Phonemes are both lost and created, apparently with roughly the same frequency.

If phonemes can be lost, it stands to reason that they can also be created. Otherwise languages would tend to have fewer and fewer phonemes, making them more and more difficult for the Hearer. There are at least two ways that new phonemes can emerge in the history of a language. In both of the ways we'll look at, the phoneme starts as the allophone of an existing phoneme.

One way in which an allophone can turn into a phoneme results from the borrowing of words from another languuage in which that phone is a separate phoneme already. We have seen that [v] was an allophone of the phoneme /f/ in Old English, not a separate phoneme. But following the Norman conquest of England in the 11th century, English borrowed many (Norman) French words. Some of these words contained [v] (a separate phoneme in French), and some of these were in positions where the [v] allophone of /f/ did not occur, for example, at the beginning of words (very). Once [v] was appearing in positions where [f] could appear, that is, once the distributions of [v] and [f] overlapped, it was a separate phoneme in English. After this the distinction between /f/ and /v/ could be used to distinguish words from each other, for example, fine and vine.

Phonemes may also emerge out of allophones when other changes combine to make the contexts for different allophones overlap. This is what happened in Old English in the case of /č/, originally an allophone of /k/ before /i/, as we saw above. When other changes caused [k] also to appear sometimes before [i], the contexts for [k] and [č] overlapped, and they were now separate phonemes, distinguishing some words from one another. These changes are summarized in the table below, which also illustrates the emergence of another phoneme in Old English, /ü/, a high front rounded vowel. (You are familiar with this phone if you happen to know French, German, Dutch, Swedish, Hungarian, Finnish, or Mandarin Chinese.) The symbol [-] represents vowel endings that are irrelevant for the discussion, and "→" represents a sound change. The table shows what happened over a period of several hundred years. The change is illustrated with two examples, the Old English words for 'kin' and 'chin'.

'kin' 'chin' Change
1 [kunni] [kinn-]
2 [kunni] [činn-] Palatalization:
[k] → [č] before [i]
3 [künni] [činn-] Vowel fronting:
[u] → [ü]
when the next vowel was [i]
4 [künn] [činn] Deletion:
some final vowels dropped
5 [kinn] [činn]Derounding:
[ü] → [i]

Originally the words for 'kin' and 'chin' began with the same consonant phoneme, realized as [k] in both words. Then, in period 2, in a change already discussed above, /k/ in the context of a following /i/ came to be realized as [č]. At this point [č] existed in the language, but only as an allophone of the phoneme /k/. That is, the allophones [č] and [k] were still in complementary distribution. In period 3, the vowel /u/ came to be fronted in the environment of an /i/ later in the word. This is an example of anticipatory assimilation because the /u/ takes on the frontness value of the following /i/. At this point [ü] was still an allophone of the phoneme /u/, however, since it occurred only in the context of an /i/ in the next syllable. Next, in period 4, some final vowels in the language were dropped. This leaves the [ü] without the context that originally motivated it. In other words, [u] and [ü] now occur in overlapping contexts, and because the distinction between them matters for the meaning of the word, [ü] has become a phoneme in the language. Finally, in period 5, as Old English was changing to Middle English, the phoneme /ü/ was lost, merging with /i/. This made it possible for [k] to occur before /i/, as it once had in the language. But the original change that caused [k] to become [č] in this context hundreds of years before no longer applied. Thus at this point [k] and [č] occurred in overlapping contexts; namely, both could occur before /i/. Since the distinction between [k] and [č] also mattered for the meaning of the word, the two phones had become separate phonemes in the language. In fact, the words for 'kin' and 'chin' already constituted a minimal pair for these two phonemes.

Inferring phonological change

Say there are two related languages A and B. In A there is a contrast between /t/ and /θ/; in B there isn't. There are two possible histories that could have resulted in this situation, starting from the ancestor language of A and B. What are they?

How can linguists figure out what changes have occurred in the history of a language? Recent changes are not a problem; there may still be older speakers whose speech is a reflection of the period before a change took place. For earlier changes, we sometimes rely on written records, though this presents several problems. First, as we have seen, orthography never does a very good job of representing phonology, especially allophonic differences, and it tends to lag behind, representing earlier pronunciation rather than current pronunciation. Second, some writing systems, such as Chinese characters, which are also used in Japanese, do not represent phonology in any direct way at all. Third, most languages are not written, and languages that are written today were not always written.

Inferring the pronunciation of an extinct language may rely mainly on what we know about its modern descendants.

For these reasons, written records can never be adequate for a full picture of phonological change. Linguists have developed another technique for inferring the past. If a change has taken place in a particular dialect or language, there are likely to be other related dialects or languages where the change has not taken place. So by examining a set of related dialects or languages, it is sometimes possible to infer how some of them have changed and what the dialect or language that is the ancestor of the whole set was like. Consider the following example from English; the table compares the forms of several words in General American and Received Pronunciation with those in the English of Northern England and Ireland.

GA, RP E. of Northern England,
Irish E.
put /pʊt/ /pʊt/
look /lʊk/ /lʊk/
but /bʌt/ /bʊt/
luck /lʌk/ /lʊk/

We see here (and more examples would make it even more obvious) that the English of Northern England and of Ireland makes no distinction between /ʊ/ and /ʌ/; there is instead a single phoneme pronounced [ʊ]. We know that these dialects (and many others) share a common ancestor dialect with General American and Received Pronunciation. The problem is that from the data here alone, there are two possibilities for the history of these phonemes. Either the ancestor English dialect made a distinction between /ʊ/ and /ʌ/, and this distinction was lost in the English of Northern Ireland and Ireland, or the ancestor dialect did not make the distinction and the distinction emerged in General American and Received Pronunciation. If we look at other dialects, we discover that the distinction is made almost everywhere except in Northern England and Ireland. This means that, if the second alternative is right, the distinction would have to have emerged a long time ago, when all of those other dialects still shared a common ancestor. If the first alternative is right, we would expect the dialects of Northern England and Ireland to be closely related to one another, that is, to constitute a subgroup within English dialects where the distinction was lost.

To figure out which alternative is right, we can look for several other sources of information. We could try to determine from linguistic or other evidence whether the dialects of Northern England and Ireland are closely related. In fact we would discover that they are not very similar, no more similar to each other than either is to RP. Or we could look for evidence from another dialect that we know diverged from the common ancestor of all of these dialects even earlier. Unfortunately this is not very helpful in this case since the evidence is somewhat mixed. Finally we could try to come up with an explanation for how the distinction could emerge, similar to what happened in the case of /č/. The story is too complicated to go into here, but it is possible to see the the split between /ʊ/ and /ʌ/ as beginning with allophonic variation and ending with the present phonemic distinction. This in fact is apparently what happened. That is, it is the dialects of Northern England and Ireland that are more like the ancestor dialect with respect to these vowels and it is the ancestor of the other dialects that changed.

Here is another example. The modern dialects of Japanese, spoken on the main Japanese islands, and Ryukyuan, spoken in the Ryukyu islands of southern Japan, are the descendants of a single language, spoken perhaps 1000 years ago. We can infer what changes have taken place in the different dialects and what the ancestor language looked like by comparing the modern dialects. In the table below are some example words in two of the dialects. We assume that an analysis of the modern dialects has already determined what the phonemes in these dialects are, so phonemic notation is used. The symbol /ɸ/ represents a voiceless bilabial fricative, and long vowels are doubled. Tone patterns are ignored (both dialects use pitch contrastively).

Standard Japanese Central Okinawan
'body' /karada/ /duu/
'bone' /hone/ /ɸuni/
'branch' /eda/ /ida/
'breath' /iki/ /ʔiiči/
'dance' /odori/ /udui/
'daytime' /hiru/ /ɸiru/
'fog' /kiri/ /čiri/
'grass' /kusa/ /kusa/
'hair' /ke/ /kii/
'man' /otoko/ /wikiga/
'open' /akete/ /ʔakiti/
'organ' /kimo/ /čimu/
'sash' /obi/ /ʔubi/
'shoulder' /kata/ /kata/
'sleeve' /sode/ /sudi/
'south' /minami/ /nisi/
'stomach' /hara/ /wata/
'sun' /hi/ /tiida/
'rain' /ame/ /ʔami/
'rock' /isi/ /ʔisi/
'west' /nisi/ /ʔiri/
'where' /doko/ /maa/
'wine' /sake/ /saki/

For any pair of related dialects or languages, some words with the same meaning will have arisen from the same form, and others won't. Even for very closely related dialects such as General American and Received Pronunciation, we will find pairs such as /'ɛlə,vetər/ and /lɪft/ (elevator, lift), forms with the same meaning but different origins. When we are interested in phonological change, we should only take into account forms that are obviously related. For the above example, words that we should ignore include the words for 'body', 'man', 'south', 'stomach', 'sun', 'west', and 'where' because the words with these meanings in the two dialects clearly have different origins. On closer examination, we see that the Okinawan word for 'south' is identical to the Japanese word for 'west'. Since these meanings are related, it appears that the origin of the forms is the same, so we can also use this pair for comparison.

The key to figuring out the phonological history of a group of modern languages is establishing correspondences between the phonemes in the languages.

Once we have found comparable pairs of words, we need to set up correspondences between pairs of phonemes or combinations of phonemes. When we find differences, we will look more closely to see what changes might have occurred in one or the other dialect. We will focus here only on the phonemes that differ in the two languages and ignore some details such as vowel length in Okinawan. The table below summarizes these. "V" represents any vowel, and "#" represents the beginning of a word.

Standard Japanese Central Okinawan
/i, e/ /i/
/o, u/ /u/
/k/ /k, č/
/#V/ /#V, #ʔV/

In each of these cases, one dialect has two forms where the other has one. As in the example of English /ʌ/ and /ʊ/, the change is either a merging of two phones into one or a splitting of one phone into two. Let's consider the vowels first. Note first that there are two similar patterns: a high vowel in Okinawan (/u/, /i/) corresponds to that same vowel and a lower vowel in Japanese (/u, o/, /i, e/). Because languages tend to be systematic, we would expect whatever holds for one of these to be true for the other as well.

Let's first consider the possibility that the parent language had only three vowels, /a, i, u/, like Central Okinawan, and a change took place in the ancestor of Standard Japanese, resulting in five vowels, /a, i, e, u, o/. As before, the explanation for the emergence of new phonemes is more complicated than the explanation for the merging of phonemes. As we've seen earlier in this section, new phonemes normally begin with an allophone occurring in some contexts but not others. So by this story, [e] would have first appeared as an allophone of /i/ in some contexts. But what contexts? As you know by now, allophonic variation often involves assimilation, where a phoneme agrees with features of preceding or following phonemes. The relevant context for a vowel could include the preceding or following consonant, or perhaps the vowel in the preceding or following syllable. But given the phonemes of these dialects, it is hard to see how any contexts would have led /i/ to be realized as [e].

What about the alternative, that the parent language had both /i/ and /e/, as in modern Standard Japanese, and that the difference disappeared in the ancestor of Okinawan? Here the story is simpler. For some reason, /e/ in this dialect began to rise, and apparently because there were not so many minimal pairs distinguished only by the difference between /i/ and /e/, /e/ merged with /i/, becoming a single phoneme. The same thing would have happened for /o/ and /u/ in this dialect.

Of course this is still a hypothesis. We could strengthen it with data from another dialect that we know diverged from the parent language of the other two relatively early. Unfortunately I'm unaware of any such data.

The order in which a set of phonological changes takes place may have important consequences for a language.

Now let's consider the case of /k/ and /č/. There are three examples of /č/ in the Okinawan data. In all cases /č/ appears before /i/. This leads us naturally to the hypothesis that /k/ came to be realized as [č] in Okinawan when it appeared before /i/, a process of palatalization (exactly the sort of change we saw for Old English above). But there is a problem with this hypothesis: in the Okinawan word /ʔakiti/, we have /k/ (that is, [k]) before /i/. Notice, however, that this /i/ in Okinawan corresponds to /e/ in Japanese. That is, in all cases where we have /ki/ in Japanese, we have /či/ in Okinawan. The solution is to propose that the two changes in Okinawan happened in a particular order. First, /k/ came to be realized as [č] when it appeared before /i/. At this point [č] might have been just an allophone of the phoneme /k/, and 'open' would still have been /ʔakete/ (or /akete/) in Okinawan. Then later, /e/ moved and merged with /i/. If the first change had stopped taking place at this time, we would now have /ʔakiti/ in Okinawan. At this point, since both [č] and [k] could appear before /i/ (and affect the meaning of the word), [č] had become a separate phoneme in the language, that is, /č/.

Note how this proposed sequence of events is similar to that postulated for the history of English. In both cases [č] first emerged as an allophone of /k/ in the context of a following /i/ (palatalization). Later another vowel — [ü] in Old English, [e] in Okinawan — came to be pronounced [i], but the old palatalization rule was no longer in effect so words in which /k/ had preceded this other vowel now had [ki]. Since both [či] and [ki] could now occur, and in different words, /č/ and /k/ had become separate phonemes.

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