1 Since the end of the nineteenth century, term used to denote the smallest sound units that can be segmented from the acoustic flow of speech and which can function as semantically distinctive units (notation: phonetic symbol between slashes, e.g. /a/). The inventory of phonemes in a given language can be determined by: (a) finding minimal pairs, i.e. two words with different meanings that differ by a single phonetic element (e.g. /g/ vs/ /k/ in gap: cap, /m/ vs /t/ in map : tap); (b) using commutation tests to isolate the phonetic elements (e.g. [g, k, m, t]) as word-initial consonants through syntagmatic segmentation and identifying them as phonemes through paradigmatic classification based on their substitutability in otherwise similar environments. In other words, the fact that each of the four expressions has a different meaning is signaled alone by the different initial consonants. (c) Phonemes are, however, not the smallest units of phonetic description, for each phoneme represents a class of phonetically similar sound variants, the allophones, which cannot be contrastively substituted for each other, i.e. cannot stand in semantically distinctive opposition. These allophones may be realized coincidentally as independent variants unaffected by their phonetic environment (free variation).
If allophonic differences are phonotactic (i.e. conditioned according to their placement/environment), languagespecific, and in complementary distribution, then the allophones are said to be ‘combinatory variants.’ Such phonetic variants cannot be freely substituted for one another. (d) Phonemes can be represented as bundles of distinctive (i.e. phonologically relevant) features (e.g. /p/ as [+stop, +bilabial −voiced, −nasal]. From the large number of articulatory and acoustic characteristics theoretically available as distinctive features, each language takes only a small number. The various definitions of what constitutes a phoneme are by no means standard; rather, depending on the theoretical thrust and perspective, the following functional aspects are stressed in the analysis: in the Prague School the semantically distinctive function, and in American structuralism the distributional conditions and operational procedures required to ascertain phonemes. For a discussion of the concept of ‘phoneme’ in generative phonology, phonology.
2 A more recent use of ‘phoneme’ is essentially unrelated to that found in linguistic technical literature. In the production of artificial language, ‘phoneme operators’ are machines that produce speech sounds. During this production, the frequency and volume of individual sounds can be modified in very small increments. Because of the modifiability of these individual sounds, technicians speak of ‘phonemes,’ even though such ‘phonemes’ do not correspond to those in a phonetic class of articulatory phonetics.
