The accentual system of the Proto-Slavic language is reconstructed as being free (i.e. phonologically unpredictable, meaning that it can occur on any syllable in the word) and mobile (i.e. accent position could change place throughout the inflectional paradigm) pitch accent system.
Proto-Slavic accent is closely related to the accentual system of some Baltic languages (Lithuanian and Latvian) with whom it shares many common innovations that occurred in the Proto-Balto-Slavic period. Deeper, it inherits from the Proto-Indo-European accent, which was also free and mobile, though the latter to a much lesser extent.
In modern languages the prototypical accent is reflected in East Slavic languages (Russian, Ukrainian and Belarusian) as stress position, in South Slavic languages as pitch accent (Slovene and Serbo-Croatian) or stress position (Bulgarian), and in West Slavic languages as vowel length.
Old acute could occur on any syllable of a word (*ba̋ba, *lopa̋ta, *golva̋), but only on long syllable; i.e. on *a, *i, *u, *y, *ě, *ę, *ǫ which are etymologically always long and diphthongs of the type *VR: *ьr, *ъr, *ьl, *ъl, *er, *or, *el, *ol which are as diphthongs always long. Phonetically it is traditionally reconstructed as a long rising tone, according to the reflex in Slovene which is rising and the pleophonic reflex in Russian which has accent on the second part (i.e. of VRV́ type). Within Balto-Slavic framework this matches with rising intonation of the cognate Latvian ⟨õ⟩ and length marks on the second part of diphthongs in Old Prussian. However, critics of this interpretation claim that one can hardly derive the Serbo-Croatian short falling tone ⟨ȍ⟩, shortness in Slovak, length in Czech and the rising intonation in Russian pleophony from the former long rising tone. Some speculate that Proto-Slavic acute was phonetically in fact something entirely different, e.g. a glottalized syllable comparable to stød in Danish, or something similar.
Short and long circumflex are traditionally marked with two different symbols, even though we're dealing with the same prosodeme on short (*e, *o, *ь, *ъ) and long (*a, *i, *u, *y, *ě, *ę, *ǫ, *VR) syllables, respectively. Circumflex occurred only on the absolute beginning of a phonetic word, and words with initial circumflex were phonologically probably unaccented. That phonological unaccentedness was manifested as a falling tone (which is confirmed by Serbo-Croatian, Slovene and Russian reflexes). On neocircumflex see below.
Short and long neoacute are also traditionally marked with two different symbols, and we're also dealing with the same prosodeme on short and long vowels. Neoacute is traditionally reconstructed as a rising intonation on the basis of Slovene and Russian, and the description of dialectal Serbo-Croatian (Chakavian) ⟨õ⟩ as a rising tone. Short neoacute has a distinct reflex in Slovak and some Russian dialects.
Since Stang (1957) three accent paradigms (or accent types) are reconstructed for Proto-Slavic, traditionally marked with letters a, b and c. Their reflexes in individual Slavic languages are usually marked as A, B, C. Stang's original reconstruction was for nominals (nouns and adjectives), and Dybo (1963) subsequently expanded these to Proto-Slavic verbs as well.
Accent paradigm a words have a fixed acute accent on one of the syllables of the stem. Examples: *ba̋ba (feminine noun), acc. *ba̋bǫ; *ga̋dъ (masculine noun), gen. *ga̋da; *kopy̋to (neuter noun), gen. *kopy̋ta; *sъmь̋rtь (i-stem noun), gen. *sъmь̋rti; *sla̋bъ m (adjective), neuter: *sla̋bo; *pa̋titi (verb), second-person plural present *pa̋tīte.
Accent paradigm b words have either a neoacute on the final syllable of the stem (*bòbъ]], *võrtīte]]) or any accent on the first syllable of the ending (*trāva̍, *nosi̋ti). Examples: *žena̍ (feminine noun), acc. *ženǫ̍; *pòpъ (masculine noun), gen. *popa̍; *selo̍ (neuter noun), gen. *sela̍; *ògnь (i-stem noun), gen. *ogni̍; *dòbrъ m (adjective), neuter: *dobro̍; *nosi̋ti (verb), second-person plural present *nòsīte.
Accent paradigm c words have a mobile, free accent (also known as lateral mobility) - either a circumflex on the first syllable (*rǭka̍: acc. *rǫ̑kǫ), an acute on a medial syllable i.e. the penultimate syllable of the ending (instr. *rǫka̋mi, *uči̋ti) or any accent on the final syllable (dat. *golsomъ̍, second-person plural present *učīte̍). Initial circumflex always "jumps" to the preceding syllable (a preposition or a conjunction) in a phonetic word; e.g. *nȃ rǭkǫ (Serbo-Croatian: nȁ rūku). Similarly, if the circumflexed word is followed by a word lacking an accent, the accent is transferred onto it: *rǭkǫ že̍. Examples: *nogà (feminine noun), acc. *nȍgǫ; *gȏlsъ (masculine noun), gen. *gȏlsa; *zvȍno (neuter noun), gen. *zvȍna; *gȏldь (i-stem noun), gen. *gȏldi; *dȏrgъ m (adjective), neuter: *dȏrgo; *čini̋ti (verb), second-person plural present *činīte̍).
|Proto-Slavic||Free, mobile pitch accent, non-distinctive length|
|South Slavic||Bulgarian||Free, mobile stress|
|Macedonian||Fixed (antepenultimate) stress|
|Serbo-Croatian||Free, mobile pitch-accent, distinctive length|
|Slovene||Free, mobile pitch-accent or stress, distinctive length|
|East Slavic||Belarusian||Free, mobile stress|
|Russian||Free, mobile stress|
|Ukrainian||Free, mobile stress|
|West Slavic||Czech||Fixed (initial) stress, length, diphthongs|
|Slovak||Fixed (initial) stress, length, diphthongs|
|Sorbian||Fixed (initial) stress, diphthongs|
|Polish||Fixed (penultimate) stress|
Proto-Slavic accent remained free and mobile in East Slavic and South Slavic. The only exception in South Slavic is Macedonian which has a fixed stress on the antepenultimate syllable in the standard language, with southern and south-western Macedonian dialects exhibiting fixed penultimate stress, and eastern dialects exhibiting free stress. In many dialects the original Proto-Slavic accent position has changed its place; e.g. in literary Serbo-Croatian retracting by one syllable which yielded the new rising pitch (the so-called Neoštokavian retraction), with old accent preserved in nonstandard dialects (Old Štokavian, Čakavian, Kajkavian). Beside phonological causes, position of Proto-Slavic accent was often lost due to the leveling out within the mobile paradigm. In Slovene stress shifts occurred in both directions depending on the old pitch and vowel quantity, yielding tonal and stress-based variants of modern literary Slovene. In West Slavic, free accent is attested at the periphery in the northern Kashubian dialects (including Slovincian, an archaic dialect extinct since the 1940s) and Polabian (spoken on Elbe in northern-central Germany, extinct since the 18th century).
Vowel length became distinctive (phonemic) in West and partially South Slavic. In West Slavic languages it became so at the expense of free stress, and was accompanied by extensive contraction due to the loss of /j/, typically resulting in a long vowel. This process was centered in the Czech area, and covered Russian and Bulgarian areas at its extremes. This new length in West Slavic was lost during the 16th century in Polish and Sorbian, and is preserved only in Czech and Slovak. Length was phonemicized in Serbo-Croatian and Slovene, depending on the pitch. In standard Serbo-Croatian no pre-tonic lengths are allowed; i.e. with Neoštokavian retraction occurring the length of old long accented syllables was retained as a post-tonic length. In Slovene, length is restricted to the stressed position, with the exception of /ə/ which is always short.
The Proto-Slavic three-way opposition of old acute, circumflex and neoacute was in its original form lost in all Slavic languages. It was reworked into a two-way opposition, in one of two typical ways:
|Language||Number of syllables||Old acute||Long neoacute||Short neoacute||Long circumflex||Short circumflex|
|Old Štokavian Serbo-Croatian||one||ȍ||ó||ȍ||ȏ||ȏ|
Serbo-Croatian: ȍ = short falling, ȏ = long falling, ò = short rising, ó = long rising, o = short vowel without distinctive tone
Slovene: ȏ = long falling, ó = long rising, ò = short rising, o = short vowel without distinctive tone
Czech and Slovak: ō = long vowel, o = short vowel, = either long or short vowel
Beside the contrastive tone (rising vs. falling), the Late Proto-Slavic also had a vowel quantity (long vs. short) which was phonemically non-distinctive. Vowels were predictably short and thus neutral with respect to length in pretonic positions further away from the accent (stress) than the first pretonic syllable. In other words, long vowels could occur in:
Old East Slavic and Old Polish loanwords in Finnish, Karelian, Estonian, Lithuanian and Latvian show that the length of the originally long vowels in Slavic (*a, *ě, *i, *u, *ǫ, *ę) is retained regardless of the intonation, the position in the word or the number of syllables. These loanwords show no trace of the old nasality of *ę and *ǫ which indicates that the original Proto-Slavic length was preserved in all positions and conditions even after the denasalisation of *ǫ and *ę.
After surveying the data with respect to stress type (acute, circumflex, neoacute), the number of the syllables in a word, the position (stressed, pretonic or posttonic) and the accentual paradigm (a, b or c), Kapović (2005) offers the following reflexes for West Slavic, and Serbo-Croatian, which have retained distinctive lengths:
|Common Slavic accented length||Common Slavic pretonic length||Common Slavic posttonic length|
|Rising||Falling||New rising||In front of less than two moras||In front of two moras||After the circumflex (a. p. c)||After the old acute (a. p. a)|
|The old acute is shortened in Serbo-Croatian to short falling accent. In Czech, it remains long in the mono- and bisyllabic words.||The old circumflex remains long falling in mono- and bisyllabic words in Serbo-Croatian, and is shortened in longer ones. It is shortened in West Slavic.||The neo-acute remains long everywhere, the number of syllables is irrelevant.||The length is preserved in front of less than two moras.||The length is shortened in front of two moras (two full syllables or a long accented syllable).||Preserved in Serbo-Croatian, shortened in West Slavic.||Preserved in Serbo-Croatian, preserved inconsistently in West Slavic.|
|Example||PSl. *vőrna > SCr. vrȁna, Cz. vrána||PSl. *mę̑so > SCr. mȇso, Cz. maso; SCr. grȃda (gen. sg.) : grȁdovi (nom. pl.)||PSl.*pǫ̃tьnīkъ > SCr. pũtnīk, Cz. poutník||PSl. *trǭba̍ > SCr. trúba, Cz. trouba||PSl. *trǭbica > SCr. trùbica, Cz. trubice||PSl. *gȍlǭbь > SCr. gȍlūb, Cz. holub||PSl. *mě̋sę̄cь > SCr. m(j)ȅsēc, Cz. měsíc|