This chapter presupposes some knowledge of phonological theory, in particular of the concepts of the phoneme, the allophone, complementary distribution and neutralization. Useful discussion of these matters can be found in Lyons (1968: ch.3), and, with reference to Spanish, Alarcos (1965), Dalbor (1980), Macpherson (1975) and Quilis and Fernández (1969).

Phonological change

Phonological change is motivated in a number of ways, although scholars are not in agreement on the number or relative importance of the factors which provoke such change. Among the main types of phonological change are the following:

Conditioned change

Conditioned change is caused (initially, usually at the allophonic level) by a neighbouring phoneme or phonemes in the spoken chain. Such change is in most cases motivated by the unconscious need to save articulatory energy and may take a number of forms:

Assimilation

Assimilation is said to occur when a phoneme is modified in one or more of its features in such a way that the phoneme becomes more similar to a neighbouring phoneme. The most frequent case is that of anticipatory (or ‘regressive’) assimilation, in which the modified phoneme precedes the modifying unit, as in the case of Latin /k/ (see also 2.5.2.2). Lat. /k/k//k/k/k/k/, until about the first century ad, appears to have had only velar articulation ([k]), but thereafter, in the spoken Latin of most areas, the allophones of /k/ used before front (i.e. palatal) vowels themselves became attracted into the palatal area (becoming at first [t∫], later further fronted to [ts], etc.