Indo-European Phonetics
General Notes

Transcription of symbols used here:
á, é, í, ó, ú - long [a], [e], [i], [o], [u] sounds
@ - Indo-European 'schwa', an indefinite sound
k', g', s' - palatal sounds
k`, p`, t`, q` - glottalized sounds
r', l', n', m' - long syllabic sonants

Writing a summary on the Proto-Indo-European phonetic system we cannot but point out the most important principles we follow describing it. We state that:

1. The Proto-Indo-European phonemes can be reconstructed using the comparative method.
2. The term "Proto-Indo-European phonetics" refers to the Late period of the Proto-languages' development, the period just before the split of the Proto-language into separate dialects (from the 4th to the 3rd millennium BC).
3. There are numerous and various concepts of reconstructing the phonetic system of Indo-European, so we do not see our analysis as the only truth, and we are always open for corrections and discussions.

True, the Indo-European studies throughout the last two centuries gave birth to at least three general trends of understanding the phonetics of the Proto-Indo-European language. The first one, generated in the 19th century by the first Indo-Europeanists, is now called traditional. The traditional reconstruction (supported by Brugmann, Meillet, Benveniste, Szemerenyi) promotes ten Indo-European vowels (5 long and 5 short) plus 'schwa', syllabic sonants (again long and short) and 2 semivowels, three sets of Indo-European stops (voiced, voiced aspirated, voiceless) plus palatal and labiovelar consonants. According to "traditionalists", there was only one spirant in Indo-European: *s. Antoine Meillet noted five main peculiarities of the Indo-European phonetic system:

1. A rich system of stops
2. Lack of spirants
3. Frequent *s and absence of its voiced counterpart *z (*z could appear only as an allophone of *s in certain positions)
4. Poor vocalism (for only *e, *o and rare *a can be considered as pure vowels, while *i, *u are partly sonants)
5. A complex system of sonants

Here is the traditional sight in charts:

i, í
u, ú
e, é
o, ó
a, á

Vowel diphthongs
ai, ei, oi, au, eu, ou

 Syllabic sonants
r, l, n, m, r', l', n', m'

    labial labiovelar dental palatal velar
Sonants nasal m   n    
liquid     r, l    
semivowel w     y  
Stops voiced b gw d g' g
voiced aspirated bh gwh dh g'h gh
voiceless p kw t k' k
Spirants       s    

All the roots analysed in this very research are given in the traditional transcription.

Ferdinand de Saussure in 1870s first gave an idea of  the 'sonant coefficient' in Proto-Indo-European which could produce long vowels in the Proto-language. Soon the laryngeal theory appeared, supported by Lindeman, Kurilowicz and others. The laryngeal theory proclaimed the new understanding of Indo-European phonetics: laryngeal phonemes should be added. The number of laryngeals (usually marked as *H) has always been a question for discussion, varying from only one to three. The discovery and deciphering of the Hittite language gave a brilliant proof of the existing of laryngeals in Indo-European: they were preserved in Hittite and Luwian tongues. Today the most detailed analysis of laryngeals confirms there used to be in fact three laryngeals: *H1, *H2, *H3 which generated lengthening of *a, *e, *o vowels in Proto-Indo-European. Except Hittite, none of known Indo-European dialects preserved any trace of laryngeals, though there have been several attempts to find their trace in Indic, Hellenic and Slavic languages.

While the laryngeal theory mainly considered the situation with vowels in Indo-European, the consonant structure elaborated by traditionalists still caused a lot of questions:

1. There is no existing language with such a system of three series of stops, so Indo-European looks typologically strange.
2. There are few, if any, secure cognate sets supporting the reconstruction of IE *b, and fewer still for *b initially than medially. In the Pokorny 1959 dictionary this phoneme is mentioned fewer than 30 times (*g, *d - each more than 80 times), and moreover the majority of cognates with it are doubtful. It it even more weird if we bear in mind that there is only one language in the world with a series of plain voiced stops that lacks a [b] (the Lifu language in Micronesia).
3. Only six languages in the world have voiced aspirates like *bh, *dh, *gh: five in India (all modern reflexes of Sanskrit) and Igbo in Africa.
3. IE suffixes never begin with voiced stops.

The first who dared to reconsider the traditional system of stops was Pedersen in 1951 but his theory was not fully acceptable. In 1972, Gamkrelidze in USSR and in 1973, Hopper in USA independently invented the glottalic theory which turned right upside down the traditional perception of Indo-European stops. The theory was described in detail in the 1984 work by Gamkrelidze & Ivanov. It suggested that there had been in fact three series of stops in the Proto-Indo-European language: glottalized stops, voiced stops (with aspirated position allophones) and voiceless stops (again with aspirated position allophones). This system looks typologically unremarkable: 8% of all world languages and 33% of languages with three stop series have such a structure of stops; 25% of  the world languages that have a series of glottalized (ejective) stops lack the bilabial [p`] so the problem of a rare IE *b was explained: according to the glottalic theory, it was in fact a glottal *p` sound.

Here is the chart of the glottalic system:

Stop consonants
    labial dental
    plain palatalized labiovelar
Stops glottalized (p`) t` k` k`' k`w
voiced  b/bh d/dh g/gh g'/g'h gw/gwh
voiceless p/ph t/th k/kh k'/k'h kw/kwh

In addition to the chart above, Gamkrelidze & Ivanov suggested the set of three Indo-European spirants: *s, *s' (palatal) and *sw (labialized): the palatal spirant was reconstructed as the famous 's-mobile' at the beginning of the word (e.g. Latin specio vs. Sanskrit pas'ya-, or Greek stigó vs. Sanskrit tejate). The labialized spirant reflects in sw- or s- in different Indo-European languages (Latin sermo vs. Gothic swaran, Lithuanian sesuo vs. Sanskrit svasar-).

Another innovation introduced by "glottalicists" was the post-velar set of stops marked as *q, *q` but their existence was not evidently proved. As a whole, the glottalic theory seems rather progressive and fits the common laws of phonology better than the traditional one. But it will surely take much time for the linguistic community to brush the things up and to reconsider the whole structure of Indo-European consonantism and the phonetic processes in various IE languages.

Nowadays it is possible to reconstruct the Proto-Indo-European phonetics, but all existing tongues of the family have had their phonetic systems changed greatly through centuries. Even the most archaic dialects spoken today in Europe and Asia have gone far from the original state of phonetics. The whole sets of consonants disappeared (like palatalized or labiovelar ones), long and short vowels coincided practically everywhere. Syllabic sonants and semivowels became simple consonants; the only one which has preserved its ancient articulation is w in Germanic languages. The most stable series of phonemes is evidently the class of sonants: *n, *m, *r, and *l were preserved in almost all dialectal groups - except maybe Indo-Iranian where the original sounds [r] and [l] coincided and became athe single [r]. Sonants have been so predictable that we will not even analyse their development in this very research. In general, the phonetic system of the Proto-Indo-European language seems far more complicated than its reflections in modern tongues of the family: the trend of simplification which restructured fully the very system of the Indo-European language influenced phonetics as well.

More information:

Historical Grammar of the Lithuanian Language (phonetics)
Grammar of the Lydian Language (phonetics)
Common Slavic Grammar (phonetics)
Historical Grammar of the Old English language (phonetics)
A Comparative Latin Grammar (phonetics)
A Survey of the Latin Phonetics - by Dmitry Pisarev
Phonology of the Gaulish Language - by Christopher Gwinn


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Gamkrelidze T., Ivanov V. The Indo-European Language and Indo-Europeans. Tbilisi, 1984.
Hopper, P.J. Glottalized and murmured occlusives in Indo-European. An international Jornal of Linguistics, v.7. 1973.
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Lindeman, F. Introduction to the Laryngeal Theory. Oxford, 1981.
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