Phonology

Phonology (Greek phone = voice/sound and logos = word/speech), is a subfield of linguistics which studies the sound system of a specific language (or languages). Whereas phonetics is about the physical production and perception of the sounds of speech, phonology describes the way sounds function within a given language or across languages.

An important part of phonology is studying which sounds are distinctive units within a language. In English, for example, /p/ and /b/ are distinctive units of sound, (i.e., they are phonemes /the difference is phonemic). This can be seen from minimal pairs such as "pin" and "bin", which mean different things, but differ only in one sound. On the other hand, /p/ is often pronounced differently depending on its position relative to other sounds, yet these different pronunciations are still considered by native speakers to be the same "sound". For example, the /p/ in "pin" is aspirated while the same phoneme in "spin" is not. In some other languages, eg Thai and Quechua, this same difference of aspiration or non-aspiration does differentiate phonemes.

In addition to the minimal meaningful sounds (the phonemes), phonology studies how sounds alternate, such as the /p/ in English described above, and topics such as syllable structure, stress, accent, and intonation.

The principles of phonological theory have also been applied to the analysis of signed languages, with gestures and their relationships as the object of study.

Representing phonemes
The writing systems of some languages are based on the phonemic principle of having one letter (or combination of letters) per phoneme and vice-versa. Ideally, speakers can correctly write whatever they can say, and can correctly read anything that is written. (In practice, this ideal is never realized.) However in English, different spellings can be used for the same phoneme (e.g., rude and food have the same vowel sounds), and the same letter (or combination of letters) can represent different phonemes (e.g., the "th" consonant sounds of thin and this are different). In order to avoid this confusion based on orthography, phonologists represent phonemes by writing them between two slashes: " / / " (but without the quotes). On the other hand, the actual sounds are enclosed by square brackets: " [ ] " (again, without quotes). While the letters between slashes may be based on spelling conventions, the letters between square brackets are usually the International Phonetic Alphabet (IPA) or some other phonetic transcription system.

Doing a phoneme inventory
Part of the phonological study of a language involves looking at data (phonetic transcriptions of the speech of native speakers) and trying to deduce what the underlying phonemes are and what the sound inventory of the language is. Even though a language may make distinctions between a small number of phonemes, speakers actually produce many more phonetic sounds. Thus, a phoneme in a particular language can be pronounced in many ways.

Looking for minimal pairs forms part of the research in studying the phoneme inventory of a language. A minimal pair is a pair of words from the same language, that differ by only a single sound, and that are recognized by speakers as being two different words. When there is a minimal pair, the two sounds constitute separate phonemes. (It is often not possible to detect all phonemes with this method so other approaches are used as well.) If two similar sounds do not constitute separate phonemes, they are called allophones of the same underlying phoneme.

Phonemic distinctions or allophones
If two similar sounds do not constitute separate phonemes, they are called allophones of the same underlying phoneme. For instance, voiceless stops can be aspirated. In English, voiceless stops at the beginning of a word are aspirated, whereas after /s/ they are not aspirated. (This can be seen by putting your fingers right in front of your lips and notice the difference in breathiness as you say 'pin' and 'spin'.) There is no English word 'pin' that starts with an unaspirated p, therefore in English, aspirated (the  means aspirated) and unaspirated [p] are allophones of an underlying phoneme /p/.

Another example of allophones in English is how the /t/ sounds in the words 'tub', 'stub', 'but', and 'butter' are all pronounced differently, yet are all perceived as "the same sound.

Another example: in English, the liquids and  are two separate phonemes (minimal pair 'life', 'rife'); however, in Korean these two liquids are allophones of the same phoneme, and the general rule is that  comes before a vowel, and  does not (e.g. Seoul, Korea). A native speaker will tell you that the in Seoul and the  in Korean are in fact the same letter. What happens is that a native Korean speaker's brain recognises the underlying phoneme, and, depending on the phonetic context (whether before a vowel or not), expresses it as either or. Another Korean speaker will hear both sounds as the underlying phoneme and think of them as the same sound. This is one reason why most people have an accent when they attempt to speak a language that they did not grow up hearing; their brains sort the sounds they hear in terms of the phonemes of their own native language.

Change of a phoneme inventory over time
The particular sounds which are phonemic in a language can change over time. At one time, and  were allophones in English, but these later changed into separate phonemes. This is one of the main factors of historical change of languages as described in historical linguistics.

Other topics in phonology
Phonology also includes topics such as assimilation, elision, epenthesis, vowel harmony, tone, non-phonemic prosody and phonotactics. Prosody includes topics such as stress and intonation.

Word stress
In some languages, stress is non-phonemic. Some examples include Finnish and all ancient Germanic languages (Old Norse, Old English and Old High German) as well as some modern Germanic languages such as Icelandic. However, in other modern-day Germanic languages such as German or English, stress is phonemically distinctive, although there are only a few minimal pairs. In German, for example,, the personal name August, contrasts with , the month August.

The distinction of stress is often seen in English words where the verb and noun forms have the same spelling. For example, consider 'rebel' the noun (which places the emphasis on the first syllable) contrasted with  'rebel' the verb (which instead puts the emphasis on the second syllable).

Another example is the pair insight and incite, where in the former the stress lies on the first syllable and in the latter on the second syllable. In American English, the words Missouri and misery are also distinguished only by stress. In Missouri, the stress lies on the penultimate syllable, but in misery it lies on the first syllable.

Development of the field
The Polish scholar Jan Baudouin de Courtenay coined the word phoneme in 1876, and his work, though often unacknowledged, is considered to be the starting point of modern phonology. He worked not only on the theory of the phoneme but also on phonetic alternations (i.e., what is now called allophony and morphophonology). His influence on Ferdinand de Saussure, the father of Structuralism, was significant.

Prince Nikolai Trubetzkoy's posthumously published work, the Principles of Phonology (1939), is considered the foundation of the Prague School of phonology. Directly influenced by Baudouin de Courtenay, Trubetskoy is considered the founder of morphophonology, though morphophonology was first recognized by Baudouin de Courtenay. Trubetzkoy split phonology into phonemics and archiphonemics; the former has had more influence than the latter. Another important figure in the Prague School was Roman Jakobson, who was one of the most prominent linguists of the twentieth century.

In 1968, Noam Chomsky and Morris Halle published The Sound Pattern of English, the basis for Generative Phonology. In this view, phonological representations (surface forms) are structures whose phonetic part is a sequence of phonemes which are made up of distinctive features. These features were an expansion of earlier work by Roman Jakobson, Gunnar Fant, and Halle. The features describe aspects of articulation and perception, are from a universally fixed set, and have the binary values + or -. Ordered phonological rules govern how this phonological representation (also called underlying representation) is transformed into the actual pronunciation (also called surface form.) An important consequence of the influence SPE had on phonological theory was the downplaying of the syllable and the emphasis on segments. Furthermore, the Generativists folded morphology into phonology, which both solved and created problems.

In the late 1960s, David Stampe introduced Natural Phonology. In this view, phonology is based on a set of universal phonological processes which interact with one another; which ones are active and which are suppressed are language-specific. Rather than acting on segments, phonological processes act on distinctive features within prosodic groups. Prosodic groups can be as small as a part of a syllable or as large as an entire utterance. Phonological processes are unordered with respect to each other and apply simultaneously (though the output of one process may be the input to another). The second-most prominent Natural Phonologist is Stampe's wife, Patricia Donegan; there are many Natural Phonologists in Europe, though also a few others in the U.S., such as Geoffrey Pullum. The principles of Natural Phonology were extended to morphology by Wolfgang Dressler, who founded Natural Morphology.

In 1976 John Goldsmith introduced autosegmental phonology. Phonological phenomena are no longer seen as one linear sequence of segments, called phonemes or feature combinations, but rather as some parallel sequences of features which reside on multiple tiers.

Government Phonology, which originated in the early 1980s as an attempt to unify theoretical notions of syntactic and phonological structures, is based on the notion that all languages necessarily follow a small set of principles and vary according to their selection of certain binary parameters. That is, all languages' phonological structures are essentially the same, but there is restricted variation that accounts for differences in surface realizations. Principles are held to be inviolable, though parameters may sometimes come into conflict. Prominent figures include Jonathan Kaye, Jean Lowenstamm, Jean-Roger Vergnaud, Monik Charette, John Harris, and many others.

In a course at the LSA summer institute in 1991, Alan Prince and Paul Smolensky developed Optimality Theory—an overall architecture for phonology according to which languages choose a pronunciation of a word that best satisfies a list of constraints which is ordered by importance: a lower-ranked constraint can be violated when the violation is necessary in order to obey a higher-ranked constraint. The approach was soon extended to morphology by John McCarthy and Alan Prince, and has become the dominant trend in phonology. Though usually unacknowledged, Optimality Theory was strongly influenced by Natural Phonology; both view phonology in terms of constraints on speakers and their production, though these constraints are formalized in very different ways.