Published online by Cambridge University Press: 12 March 2026
The class of phonetic changes in which the loss of a consonant is accompanied by the development of distinctive length in a nearby vowel has traditionally been designated by the term ‘compensatory lengthening’. We first discard cases in which the development of length and the loss of a consonant are in fact independent phenomena, and then analyse remaining examples. It is argued that such changes always involve loss of a consonant immediately adjacent to the vowel in which length subsequently appears, and that the change can be analysed quite generally into the two independently-motivated processes of weakening of a consonant to a glide (either semivocalic or laryngeal) and subsequent monophthongization of a complex syllable nucleus. The category of compensatory lengthening is thus shown not to be an independent mechanism of phonetic change. The fact that synchronic grammars sometimes contain rules of this type is argued to be an instance of the difference, in the general case, between phonetically-motivated processes and phonological rules. Conclusions are drawn for the study of the role of phonetic explanation in phonology.
It is further argued that the monophthongization involved in these examples leads to the development of length if and only if a length contrast is independently motivated in the system of the language concerned. This provides a particularly clear example of the (structuralist) principle that the phonological interpretation of a phonetic change is dependent on the structure of the system in which it takes place.