The phoneme

Many theories of phonology use the concept of the phoneme. The phoneme is the smallest unit of sound which can differentiate one word from another: in other words, phonemes make lexical distinctions. So if we take a word like ‘cat’, [kat], and swap the [k] sound for a [p] sound, we get ‘pat’ instead of ‘cat’. This is enough to establish that [k] and [p] are linguistically meaningful units of sound, i.e. phonemes. Phonemes are written between slashes, so the phonemes corresponding to the sounds [p] and [k] are represented as /p/ and /k/ respectively. Phonemes are phonological (not phonetic) units, because they relate to linguistic structure and organization; so they are abstract units. On the other hand, [p] and [k] are sounds of speech, which have a physical dimension and can be described in acoustic, auditory or articulatory terms; what is more, there are many different ways to pronounce /p/ and /k/, and transcribing them as [p] and [k] captures only some of the phonetic details we can observe about these sounds.

Phoneme theory originated in the early twentieth century, and was influential in many theories of phonology; however, in recent decades, many phonologists and phoneticians have seen phonemes as little more than a convenient fiction. One reason for this is that phonemic representations imply that speech consists of units strung together like beads on a string. This is a very unsatisfactory model of speech, because at any one point in time, we can usually hear cues for two or more speech sounds. For example, if you say the words ‘cat’, ‘kit’, ‘coot’ and isolate the [k] sounds, you will notice that they are different from one another. The tongue makes contact with the roof of the mouth at slightly different places (further forward for ‘kit’, further back for ‘coot’ and somewhere in between for ‘cat’), and the lips also have different shapes. These things make the [k] sounds sound different from one another. Now, we have the feeling, as native speakers of English, that these sounds are at some level ‘the same’; and this is what phoneme theory attempts to explain. These different sounds are allophones of the phoneme /k/: they have some things in common, and the differences between them arise from the context they are in. The differences are not seen as linguistically important, because they are predictable.

Another way to look at this is to think of the consonant as telling us something about the vowel that is coming: if you hear the kind of [k] which goes in the word ‘kit’, then before you even hear the vowel sound for real, you can tell what kind of vowel sound is coming. So in a way, the consonant and the vowel are being produced at the same time.

The question for us as phoneticians is what we make of this, and how we explain it. We will use the word ‘sound’ as an essentially neutral word which does not take one stance or another towards what we hear. It is a term chosen so as to allow us to be as descriptively rich as we would like, without committing us one way or another to whether the best account is a phonemic one or something else.

Sounds will be written enclosed in square brackets, such as [k], [a], [t] or [kat]. Phonemes, where we refer to them, will be enclosed in slash brackets such as /k/, /a/, /t/. And letters will from now on be enclosed between angled brackets like this:; but when referring to words, the convention will be: ‘cat’. We will use English spelling quite a lot, and this might seem counterintuitive in a book on English phonetics. But remember that speakers of English do not all pronounce the same words with the same phonemes, let alone the same sounds; and the only neutral way to write English is in fact its orthography: this is one reason why English spelling has been so resistant to change over the years.