Laryngeal theory

The laryngeal theory aims to produce greater regularity in the reconstruction of Proto-Indo-European phonology than in the reconstruction produced by the comparative method. Most notably, it seeks to extend the general occurrence of ablaut (apophony) to syllables that contain reconstructed vowel phonemes other than *e or *o.

In its earlier form (see below) the theory postulated three sounds in PIE (Proto-Indo-European) which combined with reconstructed *e or *o to produce vowel phonemes which would not otherwise be predicted by the rules of ablaut. It received considerable support from the decipherment of Hittite, which was discovered to be an Indo-European language. Many Hittite words were recognised as reflexes (derived words) of PIE, with a phoneme represented as ḫ corresponding to one of the hypothetical PIE sounds. Subsequent scholarship has established a set of rules by which an ever-increasing number of reflexes in daughter languages may be derived from PIE roots. The number of explanations achieved and the simplicity of the postulated system has led to widespread acceptance of the theory.