Proto-Indo-European phonology

The phonology of the Proto-Indo-European language (PIE) has been reconstructed by linguists, based on the similarities and differences among current and extinct Indo-European languages. Because PIE was not written, linguists must rely on the evidence of its earliest attested descendants, such as Hittite, Sanskrit, Ancient Greek and Latin, to reconstruct its phonology.

The reconstruction of abstract units of PIE phonological systems (i.e. segments, or phonemes in traditional phonology) is mostly fairly uncontroversial, although areas of dispute remain. Their phonetic interpretation is more difficult to establish; this pertains especially to the vowels, the so-called laryngeals, and the voiced stops.

Proto-Indo-European is traditionally reconstructed to have used the following phonemes. See the article on Indo-European sound laws for a summary of how these phonemes reflected in the various Indo-European languages.

The table gives the most common notation in modern publications; variant transcriptions are given below. Raised ʰ stands for aspiration, and raised ʷ for labialization. The *y corresponds to the palatal semivowel whose IPA transcription is [j] (and not to IPA [y]).

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