 If segments appear in the same position but the mutual substitution does not result in change of meaning, they are said to be in free variation.

     Distinctive and non-distinctive features

     Features that distinguish meaning are called distinctive features, and features do not, non-distinctive features.

     Distinctive features in one language may be non-distinctive in another.

     Phonological rules

     Phonemes are abstract sound units stored in the mind, while allophones are the actual pronunciations in speech.

     What phoneme is realized by what allophones in what specific context is another major question in phonology.

     The regularities that what sounds vary in what ways in what context are generalized and stated in phonology as rules.

     There are many phonological rules in English. Take the following ones as examples.

     [+voiced +consonant] – [-voiced]/[-voiced +consonant]_

     [-voiced +bilabial +stop] – unaspirated/[-voiced +alveolar +fricative]_

     Syllable structure

     A syllable is a phonological unit that is composed of one or more phonemes.

     Every syllable has a nucleus, which is usually a vowel.

     The nucleus may be preceded by one or more consonants called the onset and followed by one or more consonants called the coda.

     Sequence of phonemes

     Native speakers of any language intuitively know what sounds can be put together.

     Some sequences are not possible in English. The impossible sequences are called systematic gaps.

     Sequences that are possible but do not occur yet are called accidental gaps.

     When new words are coined, they may fill some accidental gaps but they will never fill systematic gaps.

     Suprasegmental features

     Features that are found over a segment or a sequence of two or more segments are called suprasegmental features.

     These features are distinctive features.

     Stress

     Stress is the perceived prominence of one or more syllabic elements over others in a word.

     Stress is a relative notion. Only words that are composed of two or more syllables have stress.

     If a word has three or more syllables, there is a primary stress and a secondary stress.

     In some languages word stress is fixed, i.e. on a certain syllable. In English, word stress is unpredictable.

     Intonation

     When we speak, we change the pitch of our voice to express ideas.

     Intonation is the variation of pitch to distinguish utterance meaning.

     The same sentence uttered with different intonation may express different attitude of the speaker.

     In English, there are three basic intonation patterns: fall, rise, fall-rise.

     Tone

     Tone is the variation of pitch to distinguish words.

     The same sequence of segments can be different words if uttered with different tones.

     Chinese is a typical tone language.

    Chapter 4 Morphology

     What is morphology?

     The total number of words stored in the brain is called the lexicon.

     Words are the smallest free units of language that unite sounds with meaning.

     Morphology is defined as the study of the internal structure and the formation of words.

     Morphemes and allomorphs

     The smallest meaningful unit of language is called a morpheme.

     A morpheme may be represented by different forms, called allomorphs.

     “zero” form of a morpheme and suppletives

     Some countable nouns do not change form to express plurality. Similarly, some regular verbs do not change form to indicate past tense. In these two cases, the noun or verb contains two morphemes, among which there is one “zero form” of a morpheme.