Laryngeal theory

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

In its earlier form (see below), the theory postulated two sounds in PIE. Combined with a reconstructed *e or *o, the sounds produce vowel phonemes that would not otherwise be predicted by the rules of ablaut. The theory received considerable support after the decipherment of Hittite, which revealed it to be an Indo-European language. Many Hittite words were shown to be derived from 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 thus achieved and the simplicity of the postulated system have both led to widespread acceptance of the theory.

In its most widely accepted version, the theory posits three phonemes in PIE: h₁, h₂ and h₃ (see below). Other daughter languages inherited the derived sounds, resulting from their merger with PIE short vowels and their subsequent loss. The phonemes are now recognised as consonants, related to articulation in the general area of the larynx, where a consonantal gesture may affect vowel quality. They are regularly known as laryngeal, but the actual place of articulation for each consonant remains a matter of debate. (see below).

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