Neutralization and Archiphonemes
Phonemes that are contrastive in certain environments may not be contrastive in all environments. In the environments where they do not contrast, the contrast is said to be neutralized. In these positions it may become less clear which phoneme a given phone represents. Some phonologists prefer not to specify a unique phoneme in such cases, since to do so would mean providing redundant or even arbitrary information – instead they use the technique of underspecification. An archiphoneme is an object sometimes used to represent an underspecified phoneme.
An example of neutralization is provided by the Russian vowels /a/ and /o/. These phonemes are contrasting in stressed syllables, but in unstressed syllables the contrast is lost, since both are reduced to the same sound, usually (for details, see Vowel reduction in Russian). In order to assign such an instance of to one of the phonemes /a/ and /o/, it is necessary to consider morphological factors (such as which of the vowels occurs in other forms of the words, or which inflectional pattern is followed). In some cases even this may not provide an unambiguous answer. A description using the approach of underspecification would not attempt to assign to a specific phoneme in some or all of these cases, although it might be assigned to an archiphoneme, written something like |A|, which reflects the two neutralized phonemes in this position.
A somewhat different example is found in English, with the three nasal phonemes /m, n, ŋ/. In word-final position these all contrast, as shown by the minimal triplet sum /sʌm/, sun /sʌn/, sung /sʌŋ/. However, before a stop such as /p, t, k/ (provided there is no morpheme boundary between them), only one of the nasals is possible in any given position: /m/ before /p/, /n/ before /t/ or /d/, and /ŋ/ before /k/, as in limp, lint, link ( /lɪmp/, /lɪnt/, /lɪŋk/). The nasals are therefore not contrastive in these environments, and according to some theorists this makes it inappropriate to assign the nasal phones heard here to any one of the phonemes (even though, in this case, the phonetic evidence is unambiguous). Instead they may analyze these phones as belonging to a single archiphoneme, written something like |N|, and state the underlying representations of limp, lint, link to be |lɪNp|, |lɪNt|, |lɪNk|.
This latter type of analysis is often associated with Nikolai Trubetzkoy of the Prague school. Archiphonemes are often notated with a capital letter within pipes, as with the examples |A| and |N| given above. Other ways the second of these might be notated include |m-n-ŋ|, {m, n, ŋ}, or |n*|.
Another example from English, but this time involving complete phonetic convergence as in the Russian example, is the flapping of /t/ and /d/ in some American English (described above under Biuniqueness). Here the words betting and bedding might both be pronounced, and if a speaker applies such flapping consistently, it would be necessary to look for morphological evidence (the pronunciation of the related forms bet and bed, for example) in order to determine which phoneme the flap represents. As in the previous examples, some theorists would prefer not to make such a determination, and simply assign the flap in both cases to a single archiphoneme, written (for example) |D|.
For a special kind of neutralization proposed in generative phonology, see absolute neutralization.
Read more about this topic: Phoneme