Remnants of former processes
At any stage a language will contain remnants of processes which were once active. Such remnants are important in reconstructing previous stages of the language concerned. For instance umlaut is a process which was once productive in English. The principle was that a high vowel or /j/ in a syllable (usually a grammatical ending) caused the vowel of the preceding syllable, if a back vowel, to be moved to a front position. This is a kind of assimilation where the frontness of the following vowel or approximant is anticipated in the preceding syllable. Now the umlaut process became inactive in the Old English period and no new instances of it arose in Middle English. But because the words affected by umlaut belonged to the core of the vocabulary — for instance names for humans, animals or parts of the body — and because such words change slowly if at all, traces of umlaut are still to be found in English.
Umlaut in English
Various changes have obscured the original process. For example tooth now has /u:/ but formerly had /o:/, compare the orthography. Teeth shows /i:/ today but derives from /e:/ which in turn once was /ø:/, the original change between singular and plural was /o:/ > /ø:/. Umlaut was not confined to the alternation of number in nouns. It could also occur with verbs, for instance those which originally showed the ending -jan underwent umlaut in the stem vowel, hence doom and deem from a very much earlier dømjan from an even earlier dōmjan.
Verner’s Law is one of the major changes in Germanic and its effects can be recognised to this day in the present-day languages. Recall that in essence it says that if the accent does not fall on an immediately preceding syllable then the onset of the following syllable is voiced. Thus one had ˡV/s/V but Vˡ/z/V for example in verbal paradigms. Now the /z/ which arose in this way was frequently subject to rhotacism so that the alternation was then /s/ ~ /r/. Indeed if the /s/ was later voiced (after rhotacism had declined as a phonological process) then the alternation may have become /z/ ~ /r/ which is what one has in was : were in present-day English.
This alternation is preserved in this paradigm but in others analogy may conceal the original alternation. Hence analogy resulted in /s/ in English lose but (later voiced due its internal position) but led to /r/ in German, that is all the /r/-forms were changed in English by analogy to those in /s/ whereas in German all the /s/ forms changed to /r/. This applies to the verb ‘to lose’, however in German the noun Verlust shows that an /s/ was originally found in the paradigm while in English the adjective forlorn ‘abandoned, scarcely likely’ as in a forlorn place, a forlorn hope (derived from a past participle) shows that there was originally an /r/ in the paradigm.
Reflexes of older words
Older forms may still be found in fixed expressions. In English there is an expression to wend one's weary way (taken from a line in Thomas Grey’s Elegy in a Country Courtyard) contains the verb wend (cf. German wenden) which is an older verb meaning ‘to go’. This verb has died out but the past form of the present verb go derives from this source. This process is known as suppletion, the appearance of a form from one paradigm in another paradigm in which it did not originally occur.
Reflexes of older words may be available in different word classes. For instance the only reflex of Old English wyrd ‘destiny’ is the present-day adjective weird. A reflex may also be contained in a compound as with Old English wer (a common Indo-European word, cf. Latin virus) does not exist anymore but is found in the compound werewolf ‘man-wolf’. Another Old English word for ‘man’ guma is contained in bridegroom (originally brydguma) but by folk etymology the second element was re-interpreted as groom.
Remnants of processes involving vowels are also to be found in Modern English. Take the alternation keep : kept which has a long : short vowel alternation because in Old English there was a general shortening of vowels before double consonants: cēpan : cēpte became cēpan : cepte. This also applied to cases of gemination as with blēdan : bledde (< blēdde) which with the later loss of geminates resulted in bleed : bled.
WORKING BACKWARDS: UNRAVELLING SOUND CHANGES The techniques illustrated above all involve the undoing of changes in order to arrive at any original form of some earlier stage of a language. This working backwards is a common method for gaining knowledge of former periods. It consists basically of reversing known changes in order to gain time depth in one’s investigation. A complete example of this technique is offered here to show that useful results can be achieved here. The goal of the present exercise is to show what the original singular ~ plural alternation was for a word pair which shows an irregular alternation in Modern English, mouse ~ mice.
|Original alternation||/mu:s/-sg : /mu:si/-PL|
|/mu:s/ + vowel shift||/maus/|
|/mu:si/ + i-umlaut||/my:si/|
|/my:si/ + inflectional loss||/my:s/|
|/my:s/ + unrounding||/mi:s/|
|/mi:s/ + vowel shift||/mais/|