A phoneme ( ) is a set of similar speech sounds that are perceptually regarded by the speakers of a language as a single basic sound—the smallest possible phonetic unit—that helps distinguish one word from another. All languages contain phonemes (or the spatial–gestural equivalent in sign languages), and all spoken languages include both consonant and vowel phonemes. Phonemes are studied under phonology, a branch of linguistics.
Phonemes are traditionally represented, when written, as a glyph (a character) enclosed within two forward-sloping slashes . For example, indicates the vowel phoneme, or set of possible sounds, used in the middle of the English word pot. The exact phonetic reality of this phoneme varies by accent, with the pronunciation in many British and Australian accents, in many US and Irish accents, in Great Lakes accents of the US, etc. Still, counts as one phoneme because it contrasts with, say, the of put or of pit.
Overview
The words cell and set have the same sequence of sounds except for the final consonant: thus, versus in the International Phonetic Alphabet (IPA), which is a writing system that can be used to represent phonemes. Since and alone distinguish the spoken words cell and set, and are examples of phonemes of the English language. Specifically they are consonant phonemes, along with the , while is a vowel phoneme. English spelling does not always closely align with its phonemes. For example, the English words knot, nut, and gnat all share the consonant phonemes and , differing only by their vowel phonemes: , , and , respectively. Another example of phonemic transcription is : the notation for a sequence of four phonemes—, , , and —that constitutes the pronunciation of the word pushed.
Phonemes, or word-distinguishing sounds (or sets of sounds), are perceived differently by users of one language versus another. For example, and are separate phonemes in English as they distinguish words like sin from words like sing ( versus ), but they constitute a single phoneme in other languages, such as Spanish, in which and for instance are interpreted by Spanish speakers as merely regional or dialect-specific pronunciations of the same word (: the Spanish word for "bread"). Such spoken variations of a single phoneme are known by linguists as allophones. On the other hand, and are usually heard as variations on one phoneme in English, though they are completely separate phonemes in other languages, like French, which distinguishes words such as rue, "street" from roue, "wheel" .
Linguists use slashes in the IPA to transcribe phonemes, and square brackets to transcribe more precise pronunciation details, including allophones; they describe this distinction as phonemic versus phonetic. Thus, the pronunciations of tap versus tab, or pat versus bat, can be represented phonemically and are written between slashes (, , etc.), while nuances of exactly how speakers pronounce are phonetic and written between brackets, such as for the p in spit versus for the p in pit, which in English is an aspirated allophone of /p/ (i.e., pronounced with an extra burst of air).
Conceptual basis; theory of the definition of phonemes There are many views as to exactly what phonemes are and how a given language should be analyzed in phonemic terms. Generally, a phoneme is regarded as an abstraction of a set (or equivalence class) of spoken sound variations that are nevertheless perceived as a single basic unit of sound by the ordinary native speakers of a given language. While phonemes are considered abstracted, underlying representations for sound segments within words, the corresponding phonetic realizations of those phonemes—each phoneme with its various allophones—constitute the surface form that is actually uttered and heard. Allophones each have technically different articulations inside particular words or particular environments within words, yet these differences do not create any meaningful distinctions. Alternatively, at least one of those articulations could be feasibly used in all such words with these words still being recognized as such by users of the language. An example in American English is that the sound spelled with the symbol t is usually articulated with a glottal stop (or a similar glottalized sound) in the word cat, an alveolar flap in dating, an alveolar plosive in stick, and an aspirated alveolar plosive in tie; however, American English speakers perceive or "hear" all of these sounds (usually with no conscious effort) as merely being allophones of a single phoneme: the one traditionally represented in the IPA as .
For computer-typing purposes, systems such as X-SAMPA exist to represent IPA symbols using only ASCII characters. However, descriptions of particular languages may use different conventional symbols to represent the phonemes of those languages. For languages whose writing systems employ the phonemic principle, ordinary letters may be used to denote phonemes, although this approach is often imperfect, as pronunciations naturally shift in a language over time, rendering previous spelling systems outdated or no longer closely representative of the sounds of the language (see further the section headed , below).
Assignment of speech sounds to phonemes
A phoneme is a sound or a group of different sounds perceived to have the same function by speakers of the language or dialect in question. An example is the English phoneme , which occurs in words such as cat, kit, scat, skit. Although most native speakers do not notice this, in most English dialects, the "c/k" sounds in these words are not identical: in , the sound is aspirated, but in , it is unaspirated. The words, therefore, contain different speech sounds, or phones, transcribed for the aspirated form and for the unaspirated one. These different sounds are nonetheless considered to belong to the same phoneme, because if a speaker used one instead of the other, the meaning of the word would not change: using the aspirated form in skill might sound odd, but the word would still be recognized. By contrast, some other sounds would cause a change in meaning if substituted: for example, substitution of the sound would produce the different word still, and that sound must therefore be considered to represent a different phoneme (the phoneme ).
The above shows that in English, and are allophones of a single phoneme . In some languages, however, and are perceived by native speakers as significantly different sounds, and substituting one for the other can change the meaning of a word. In those languages, therefore, the two sounds represent different phonemes. For example, in Icelandic, is the first sound of , meaning "cheerful", but is the first sound of , meaning "riddles". Icelandic, therefore, has two separate phonemes and .
Minimal pairs A pair of words like and (above) that differ only in one phone is called a minimal pair for the two alternative phones in question (in this case, and ). The existence of minimal pairs is a common test to decide whether two phones represent different phonemes or are allophones of the same phoneme.
To take another example, the minimal pair tip and dip illustrates that in English, and belong to separate phonemes, and ; since the words have different meanings, English-speakers must be conscious of the distinction between the two sounds.
Signed languages, such as American Sign Language (ASL), also have minimal pairs, differing only in (exactly) one of the signs' parameters: handshape, movement, location, palm orientation, and nonmanual signal or marker. A minimal pair may exist in the signed language if the basic sign stays the same, but one of the parameters changes.
However, the absence of minimal pairs for a given pair of phones does not always mean that they belong to the same phoneme: they may be so dissimilar phonetically that it is unlikely for speakers to perceive them as the same sound. For example, English has no minimal pair for the sounds (as in hat) and (as in bang), and the fact that they can be shown to be in complementary distribution could be used to argue for their being allophones of the same phoneme. However, they are so dissimilar phonetically that they are considered separate phonemes. A case like this shows that sometimes it is the systemic distinctions and not the lexical context which are decisive in establishing phonemes. This implies that the phoneme should be defined as the smallest phonological unit which is contrastive at a lexical level or distinctive at a systemic level.
Phonologists have sometimes had recourse to "near minimal pairs" to show that speakers of the language perceive two sounds as significantly different even if no exact minimal pair exists in the lexicon. It is challenging to find a minimal pair to distinguish English from , yet it seems uncontroversial to claim that the two consonants are distinct phonemes. The two words pressure and pleasure can serve as a near minimal pair. The reason why this is still acceptable proof of phonemehood is that there is nothing about the additional difference ( vs. ) that can be expected to somehow condition a voicing difference for a single underlying postalveolar fricative. One can, however, find true minimal pairs for and if less common words are considered. For example, Confucian and confusion are a valid minimal pair.
Suprasegmental phonemes Besides segmental phonemes such as vowels and consonants, there are also suprasegmental features of pronunciation (such as tone and stress, syllable boundaries and other forms of juncture, nasalization and vowel harmony), which, in many languages, change the meaning of words and so are phonemic.
Phonemic stress is encountered in languages such as English. For example, there are two words spelled invite: one is a verb and is stressed on the second syllable; the other is a noun and stressed on the first syllable (without changing any of the individual sounds). The position of the stress distinguishes the words and so a full phonemic specification would include indication of the position of the stress: for the verb, for the noun. In other languages, such as French, word stress cannot have this function (its position is generally predictable) and so it is not phonemic (and therefore not usually indicated in dictionaries).
Phonemic tones are found in languages such as Mandarin Chinese in which a given syllable can have five different tonal pronunciations:
+ Minimal set for phonemic tone in Mandarin Chinese Tone number 1 2 3 4 5 Hanzi Pinyin IPA Gloss mother hemp horse scold question particle
The tone "phonemes" in such languages are sometimes called tonemes. Languages such as English do not have phonemic tone, but they use intonation for functions such as emphasis and attitude.
Distribution of allophones When a phoneme has more than one allophone, the one actually heard at a given occurrence of that phoneme may be dependent on the phonetic environment (surrounding sounds). Allophones that normally cannot appear in the same environment are said to be in complementary distribution. In other cases, the choice of allophone may be dependent on the individual speaker or other unpredictable factors. Such allophones are said to be in free variation, but allophones are still selected in a specific phonetic context, not the other way around.
Background and related ideas