What is Phonology?

Whereas phonetics is the study of sounds and is concerned with the production, audition and perception of of speech sounds (called phones), phonology describes the way sounds function within a given language and operates at the level of sound systems and abstract sound units. Knowing the sounds of a language is only a small part of phonology. This importance is shown by the fact that you can change one word into another by simply changing one sound. Consider the differences between the words time and dime. The words are identical except for the first sound. [t] and [d] can therefore distinguish words, and are called contrasting sounds. They are distinctive sounds in English, and all distinctive sounds are classified as phonemes.

Minimal Pairs
Minimal pairs are words with different meanings that have the same sounds except for one. These contrasting sounds can either be consonants or vowels. The words pin and bin are minimal pairs because they are exactly the same except for the first sound. The words read and rude are also exactly the same except for the vowel sound. The examples from above, time and dime, are also minimal pairs. In effect, words with one contrastive sound are minimal pairs. Another feature of minimal pairs is overlapping distribution. Sounds that occur in phonetic environments that are identical are said to be in overlapping distribution. The sounds of [ɪn] from pin and bin are in overlapping distribution because they occur in both words. The same is true for three and through. The sounds of [θr] is in overlapping distribution because they occur in both words as well.

Free Variation
Some words in English are pronounced differently by different speakers. This is most noticeable among American English speakers and British English speakers, as well as dialectal differences. This is evidenced in the ways neither, for example, can be pronounced. American English pronunciation tends to be [niðər], while British English pronunciation is [najðər].

Phones and Allophones
Phonemes are not physical sounds. They are abstract mental representations of the phonological units of a language. Phones are considered to be any single speech sound of which phonemes are made. Phonemes are a family of phones regarded as a single sound and represented by the same symbol. The different phones that are the realization of a phoneme are called allophones of that phoneme. The use of allophones is not random, but rule-governed. No one is taught these rules as they are learned subconsciously when the native language is acquired. To distinguish between a phoneme and its allophones, I will use slashes // to enclose phonemes and brackets [] to enclose allophones or phones. For example, [i] and [ĩ] are allophones of the phoneme /i/; [ɪ] and [ɪ̃] are allophones of the phoneme /ɪ/.

Complementary Distribution
If two sounds are allophones of the same phoneme, they are said to be in complementary distribution. These sounds cannot occur in minimal pairs and they cannot change the meaning of otherwise identical words. If you interchange the sounds, you will only change the pronunciation of the words, not the meaning. Native speakers of the language regard the two allophones as variations of the same sound. To hear this, start to say the word cool (your lips should be pursed in anticipation of /u/ sound), but then say kill instead (with your lips still pursed.) Your pronunciation of kill should sound strange because cool and kill are pronounced with different allophones of the phoneme /k/.

Nasalized vowels are allophones of the same phoneme in English. Take, for example, the sounds in bad and ban. The phoneme is /æ/, however the allophones are [æ] and [æ̃]. Yet in French, nasalized vowels are not allophones of the same phonemes. They are separate phonemes. The words beau [bo] and bon [bõ] are not in complementary distribution because they are minimal pairs and have contrasting sounds. Changing the sounds changes the meaning of the words. This is just one example of differences between languages.

Phonological Rules
Assimilation: sounds become more like neighboring sounds, allowing for ease of articulation or pronunciation; such as vowels are nasalized before nasal consonants
- Harmony: non-adjacent vowels become more similar by sharing a feature or set of features (common in Finnish)
- Gemination: sound becomes identical to an adjacent sound
- Regressive Assimilation: sound on left is the target, and sound on right is the trigger

Dissimilation: sounds become less like neighboring sounds; these rules are quite rare, but one example in English is [fɪfθ] becoming [fɪft] (/f/ and /θ/ are both fricatives, but /t/ is a stop)

Epenthesis: insertion of a sound, e.g. Latin "homre" became Spanish "hombre"
- Prothesis: insertion of vowel sound at beginning of word
- Anaptyxis: vowel sound with predictable quality is inserted word-internally
- Paragoge: insertion of vowel sound at end of word
- Excrescence: consonant sound inserted between other consonants (also called stop-intrusion)

Deletion: deletion of a sound; e.g. French word-final consonants are deleted when the next word begins with a consonant (but are retained when the following word begins with a vowel)
- Aphaeresis: vowel sound deleted at beginning of word
- Syncope: vowel sound is deleted word-internally
- Apocope: vowel sound deleted at end of word

Metathesis: reordering of phonemes; in some dialects of English, the word asked is pronounced [æks]; children's speech shows many cases of metathesis such as aminal for animal

Lenition: consonant changes to a weaker manner of articulation; voiced stop becomes a fricative, fricative becomes a glide, etc.

Palatalization: sound becomes palatal when adjacent to a front vowel Compensatory Lengthening: sound becomes long as a result of sound loss, e.g. Latin "octo" became Italian "otto"

Assimilation in English
An interesting observation of assimilation rules is evidenced in the formation of plurals and the past tense in English. When pluralizing nouns, the last letter is pronounced as either [s], [z], or [əz]. When forming past tenses of verbs, the -ed ending is pronounced as either [t], [d], [əd]. If you were to sort words into three columns, you would be able to tell why certain words are followed by certain sounds:

Hopefully, you can determine which consonants produce which sounds. In the nouns, /s/ is added after voiceless consonants, and /z/ is added after voiced consonants. /əz/ is added after sibilants. For the verbs, /t/ is added after voiceless consonants, and /d/ is added after voiced consonants. /əd/ is added after alveolar stops. The great thing about this is that no one ever taught you this in school. But thanks to linguistics, you now know why there are different sounds (because of assimiliation rules, the consonants become more like their neighboring consonants.)

Writing Rules
A general phonological rule is A → B / D __ E (said: A becomes B when it occurs between D and E) Other symbols in rule writing include: C = any obstruent, V = any vowel, Ø = nothing, # = word boundary, ( ) = optional, and { } = either/or. A deletion rule is A → Ø / E __ (A is deleted when it occurs after E) and an insertion rule is Ø → A / E __ (A is inserted when it occurs after E).

Alpha notation is used to collapse similar assimilation rules into one. C → [Α voice] / __ [Α voice] (An obstruent becomes voiced when it occurs before a voiced obstruent AND an obstruent becomes voiceless when it occurs before a voiceless obstruent.) Similarly, it can be used for dissimilation rules too. C → [-Α voice] / __ [Α voice] (An obstruent becomes voiced when it occurs before a voiceless obstruent AND an obstruent becomes voiceless when it occurs before a voiced obstruent.) Gemination rules are written as C1C2 → C2C2 (for example, pd → dd)

Syllable Structure
There are three peaks to a syllable: nucleus (vowel), onset (consonant before nucleus) and coda (consonant after nucleus.) The onset and coda are both optional, meaning that a syllable could contain a vowel and nothing else. The nucleus is required in every syllable by definition. The order of the peaks is always onset - nucleus - coda. All languages permit open syllables (Consonant + Vowel), but not all languages allow closed syllables (Consonant + Vowel + Consonant). Languages that only allow open syllables are called CV languages. In addition to not allowing codas, some CV languages also have constraints on the number of consonants allowed in the onset.

The sonority profile dictates that sonority must rise to the nucleus and fall to the coda in every language. The sonority scale (from most to least sonorous) is vowels - glides - liquids - nasals - obstruents. Sonority must rise in the onset, but the sounds cannot be adjacent to or share a place of articulation (except [s] in English) nor can there be more than two consonants in the onset. This explains why English allows some consonant combinations, but not others. For example, price [prajs] is a well-formed syllable and word because the sonority rises in the onset (p, an obstruent, is less sonorous than r, a liquid); however, rpice [rpajs] is not a syllable in English because the sonority does not rise in the onset.

The Maximality Condition states that onsets are as large as possible up to the well-formedness rules of a language. Onsets are always preferred over codas when syllabifying words. There are also constraints that state the maximum number of consonants between two vowels is four; onsets and codas have two consonants maximally; and onsets and codas can be bigger only at the edges of words.