Russian has five to six vowels in stressed syllables, /i, u, e, o, a/ and in some analyses /ɨ/, but in most cases these vowels have merged to only two to four vowels when unstressed: /i, u, a/ (or /ɨ, u, a/) after hard consonants and /i, u/ after soft ones.

A long-standing dispute among linguists is whether Russian has five vowel phonemes or six; that is, scholars disagree as to whether [ɨ] constitutes an allophone of /i/ or if there is an independent phoneme /ɨ/. The five-vowel analysis, taken up by the Moscow school, rests on the complementary distribution of [ɨ] and [i], with the former occurring after hard (non-palatalized) consonants (e.g. жить [ʐɨtʲ]^ⓘ 'to live', шип [ʂɨp]^ⓘ 'thorn, spine', цирк [t͡sɨrk]^ⓘ 'circus', etc.) and [i] after soft (palatalized) consonants (e.g. щит [ɕːit]^ⓘ 'shield', чин [t͡ɕin]^ⓘ 'rank', etc.). The allophony of the stressed variant of the open /a/ is largely the same, yet no scholar considers [ä] and [æ] to be separate phonemes^{[citation needed]} (which they are in e.g. Slovak and Australian English).

The six-vowel view, held by the Saint-Petersburg (Leningrad) phonology school, points to several phenomena to make its case:

• Native Russian speakers' ability to articulate [ɨ] in isolation: for example, in the names of the letters ⟨и⟩ and ⟨ы⟩.^[1]
• Rare instances of word-initial [ɨ], including the minimal pair и́кать 'to produce the sound и' and ы́кать 'to produce the sound ы',^[2] as well as borrowed names and toponyms, like Ыб [ɨp]^ⓘ, the name of a river and several villages in the Komi Republic.
• Morphological alternations between non-palatalized consonants without any following vowel or before ы and palatalized consonants before и, like гото́в [ɡʌˈtof]^ⓘ ('ready' adjective, masculine, short-form), гото́вый [ɡʌˈtovɨj]^ⓘ ('ready' adjective, masculine), and гото́вить [ɡʌˈtovʲɪtʲ]^ⓘ ('to get ready; to prepare' verb, transitive), signifying that и palatalizes an inherently non-palatalized underlying consonant while ы does not.^[3]

The most popular view among linguists (and the one taken up in this article) is that of the Moscow school,^[2] though Russian pedagogy has typically taught that there are six vowels (the term phoneme is not used).^[4]

Reconstructions of Proto-Slavic show that *i and *y (which correspond to [i] and [ɨ]) were separate phonemes. On the other hand, after the first palatalization, Old East Slavic *i and *y contrasted only after alveolars and labials: after palatals only *i occurred, and after velars only *y occurred. With the development of phonemic palatalized alveolars and labials, *i and *y no longer contrasted in any environment and were reinterpreted as allophones of each other, becoming a single phoneme /i/. Even so, this reinterpretation entailed no mergers and no change in the pronunciation. Subsequently, sometime between the twelfth and fourteenth centuries, the allophone of /i/ occurring after a velar consonant changed from [ɨ] to [i] with subsequent palatalization of the velar, turning old Russian хытрыи [ˈxɨtrɨj] into modern хитрый [ˈxʲitrɨj] and old гыбкыи [ˈɡɨpkɨj] into modern гибкий [ˈɡʲipkʲij].^[5]

Russian vowels are subject to considerable allophony, subject to both stress and the palatalization of neighboring consonants. In most unstressed positions, in fact, only three phonemes are distinguished after hard consonants, and only two after soft consonants. Unstressed /o/ and /a/ have merged to /a/ (a phenomenon known as Russian: а́канье, romanized: ákan'je); unstressed /i/ and /e/ have merged to /i/ (Russian: и́канье, romanized: íkan'je); and all four unstressed vowels have merged after soft consonants, except in the absolute final position in a word. None of these mergers are represented in writing.

When a preceding consonant is hard, /i/ is retracted to [ɨ]. Formant studies in Padgett (2001) demonstrate that [ɨ] is better characterized as slightly diphthongized from the velarization of the preceding consonant,^[6] implying that a phonological pattern of using velarization to enhance perceptual distinctiveness between hard and soft consonants is strongest before /i/. When unstressed, /i/ becomes near-close; that is, [ɨ̞] following a hard consonant and [ɪ] in most other environments.^[7] Between soft consonants, stressed /i/ is raised,^[8] as in пить [pʲi̝tʲ]^ⓘ ('to drink'). When preceded and followed by coronal or dorsal consonants, [ɨ] is fronted to [ɨ̟].^[9] After a cluster of a labial and /ɫ/, [ɨ] is retracted, as in плыть [pɫɨ̠tʲ]^ⓘ ('to float'); it is also slightly diphthongized to [ɯ̟ɨ̟].^[9]

In native words, /e/ only follows unpaired (i.e. the retroflexes and /ts/) and soft consonants. After soft consonants (but not before), it is a mid vowel [ɛ̝] (hereafter represented without the diacritic, for simplicity), while a following soft consonant raises it to close-mid [e]. Another allophone, an open-mid [ɛ], occurs word-initially and between hard consonants.^[10] Preceding hard consonants retract /e/ to [ɛ̠] and [e̠]^[11] so that жест ('gesture') and цель ('target') are pronounced [ʐɛ̠st]^ⓘ and [tse̠lʲ]^ⓘ respectively.

In words borrowed from other languages, /e/ often follows hard consonants; this foreign pronunciation usually persists in Russian for many years until the word is more fully adopted into Russian.^[12] For instance, шофёр (from French chauffeur) was pronounced [ʂoˈfɛr]^ⓘ in the early twentieth century,^[13] but is now pronounced [ʂʌˈfʲɵr]^ⓘ. On the other hand, the pronunciations of words such as отель [ʌˈtelʲ]^ⓘ ('hotel') retain the hard consonants despite a long presence in the language.

Between soft consonants, /a/ becomes [æ],^[14] as in пять [pʲætʲ]^ⓘ ('five'). When not following a soft consonant, /a/ is retracted to [ɑ̟] before /ɫ/ as in палка [ˈpɑ̟ɫkə]^ⓘ ('stick').^[14]

For most speakers, /o/ is a mid vowel [o̞], but it can be a more open [ɔ] for some speakers.^[15] Following a soft consonant, /o/ is centralized and raised to [ɵ] as in тётя [ˈtʲɵtʲə]^ⓘ ('aunt').^[16][17]

As with the other back vowels, /u/ is centralized to [ʉ] between soft consonants, as in чуть [tɕʉtʲ]^ⓘ ('narrowly'). When unstressed, /u/ becomes near-close; central [ʉ̞] between soft consonants, centralized back [ʊ] in other positions.^[18]

Russian unstressed vowels have lower intensity and lower energy. They are typically shorter than stressed vowels, and /a e o i/ in most unstressed positions tend to undergo mergers for most dialects:^[19]

• /o/ has merged with /a/: for instance, валы́ 'bulwarks' and волы́ 'oxen' are both pronounced /vaˈɫi/, phonetically [vʌˈɫɨ]^ⓘ.
• /e/ has merged with /i/: for instance, лиса́ (lisá) 'fox' and леса́ 'forests' are both pronounced /lʲiˈsa/, phonetically [lʲɪˈsa]^ⓘ.^{[example needed]}
• /a/ and /o/^[20] have merged with /i/ after soft consonants: for instance, ме́сяц (mésjats) 'month' is pronounced /ˈmʲesʲits/, phonetically [ˈmʲesʲɪts]^ⓘ.

The merger of unstressed /e/ and /i/ in particular is less universal in the pretonic (pre-accented) position than that of unstressed /o/ and /a/. For example, speakers of some rural dialects as well as the "Old Petersburgian" pronunciation may have the latter but not the former merger, distinguishing between лиса́ [lʲɪˈsa] and леса́ [lʲɘˈsa], but not between валы́ and волы́ (both [vʌˈɫɨ]). The distinction in some loanwords between unstressed /e/ and /i/, or /o/ and /a/ is codified in some pronunciation dictionaries (Avanesov (1985:663), Zarva (1993:15)), for example, фо́рте [ˈfortɛ] and ве́то [ˈvʲeto].

Unstressed vowels (except /o/) are preserved word-finally, for example in second-person plural or formal verb forms with the ending -те, such as де́лаете ("you do") /ˈdʲeɫajitʲe/ (phonetically [ˈdʲeɫə(j)ɪtʲe]). The same applies for vowels starting a word.^[21]

As a result, in most unstressed positions, only three vowel phonemes are distinguished after hard consonants (/u/, /a ~ o/, and /e ~ i/), and only two after soft consonants (/u/ and /a ~ o ~ e ~ i/). For the most part, Russian orthography (as opposed to that of the closely related Belarusian) does not reflect vowel reduction. This can be seen in Russian не́бо (nébo) as opposed to Belarusian не́ба (néba) "sky", both of which can be phonemically analyzed as /ˈnʲeba/ and morphophonemically as |ˈnʲebo|, as the nominative singular ending of neuter nouns is [o] when stressed: compare Russian село́ [sʲɪˈɫo], Belarusian сяло́ [sʲaˈɫo] "village".

In terms of actual pronunciation, there are at least two different levels of vowel reduction: vowels are less reduced when a syllable immediately precedes the stressed one, and more reduced in other positions.^[22] This is particularly visible in the realization of unstressed /o/ and /a/, where a less-reduced allophone [ʌ] appears alongside a more-reduced allophone [ə].

The pronunciation of unstressed /o ~ a/ is as follows:

1. [ʌ] (sometimes transcribed as [ɐ]; the latter is phonetically correct for the standard Moscow pronunciation, whereas the former is phonetically correct for the standard Saint Petersburg pronunciation;^[23] this article uses only the symbol [ʌ]) appears in the following positions:
   • In the syllable immediately before the stress, when a hard consonant precedes:^[24] паро́м [pʌˈrom]^ⓘ ('ferry'), трава́ [trʌˈva]^ⓘ ('grass').
   • In absolute word-initial position.^[25]
   • In hiatus, when the vowel occurs twice without a consonant between; this is written ⟨aa⟩, ⟨ao⟩, ⟨oa⟩, or ⟨oo⟩:^[25] сообража́ть [sʌʌbrʌˈʐatʲ]^ⓘ ('to use common sense, to reason').
2. [ə] appears elsewhere, when a hard consonant precedes: о́блако [ˈobɫəkə]^ⓘ ('cloud').
   • In absolute word-final position, [ʌ] may occur instead, especially at the end of a syntagma.^[26]
3. When a soft consonant or /j/ precedes, both /o/ and /a/ merge with /i/ and are pronounced as [ɪ]. Example: язы́к [jɪˈzɨk]^ⓘ ('tongue'), ежи́ [jɪˈʐɨ]^ⓘ ('hedgehogs') (/o/ is written as ⟨e⟩ in these positions; compare ёж [ˈjoʂ]^ⓘ 'hedgehog').
   • This merger also tends to occur after formerly soft consonants now pronounced hard (/ʐ/, /ʂ/, /ts/),^[27] where the pronunciation [ɨ̞]^[28] occurs; e.g. шевели́ть [ʂɨvʲɪˈlʲitʲ] 'to stir ~ to move ~ to bulge'. This always occurs when the spelling uses the soft vowel variants, e.g. жена́ [ʐɨ̞ˈna]^ⓘ ('wife') vs. жёны [ˈʐonɨ] ('wives'). However, it also occurs in a few word roots where the spelling writes a hard /a/.^[29][30] Examples:
     • жаль- 'regret': e.g. жале́ть [ʐɨ̞ˈlʲetʲ]^ⓘ ('to regret'), к сожале́нию [ksəʐɨ̞ˈlʲenʲɪju]^ⓘ ('unfortunately').
     • ло́шадь 'horse', e.g. лошаде́й, [ɫəʂɨ̞ˈdʲej]^ⓘ (pl. gen. and acc.).
     • -дцать- in numbers: e.g. двадцати́ [dvətsɨ̞ˈtʲi]^ⓘ ('twenty [gen., dat., prep.]'), тридцатью́ [trʲɪtsɨˈtʲju]^ⓘ ('thirty [instr.]').
     • ржано́й [rʐɨ̞ˈnoj]^ⓘ ('rye [adj. m. nom.]').
     • жасми́н [ʐɨ̞ˈsmʲin]^ⓘ ('jasmine').
4. These processes occur even across word boundaries as in под морем [pʌd‿ˈmorʲɪm] ('under the sea').

The pronunciation of unstressed /e ~ i/ is [ɪ] after soft consonants and /j/, and word-initially (эта́п [ɪˈtap]^ⓘ ('stage'); икра́ [ɪˈkra]^ⓘ ('roe'); диви́ть [dʲɪˈvʲitʲ] ('to surprise'), etc.), but [ɨ̞] after hard consonants (дыша́ть [dɨ̞ˈʂatʲ]^ⓘ ('to breathe')). When in a word-final position after /ʐ/, /ʂ/ or /ts/ it might have an even more open allophone [ɘ], as in полоте́нце [pəɫɐˈtʲent͡sə]^ⓘ ('towel').^{[citation needed]}

There are a number of exceptions to the above vowel-reduction rules:

• Vowels may not merge in foreign borrowings,^[31][32][33] particularly with unusual or recently borrowed words such as ра́дио, [ˈradʲɪo]^ⓘ 'radio'. In such words, unstressed /a/ may be pronounced as [ʌ], regardless of context; unstressed /e/ does not merge with /i/ in initial position or after vowels, so word pairs like эмигра́нт and иммигра́нт, or эмити́ровать and имити́ровать, differ in pronunciation.^{[citation needed]}
• Across certain word-final inflections, the reductions do not completely apply. For example, after soft or unpaired consonants, unstressed /a/, /e/ and /i/ of a final syllable may be distinguished from each other.^[34][35] For example, жи́тели [ˈʐɨtʲɪlʲɪ]^ⓘ ('residents') contrasts with both (о) жи́теле [(ʌ) ˈʐɨtʲɪlʲɪ̞]^ⓘ ('[about] a resident') and жи́теля [ˈʐɨtʲɪlʲə]^ⓘ ('(of) a resident'). Also, хо́дит [ˈxodʲɪt] ('he goes') and хо́дят [ˈxodʲət] ('they go').^[36]
• If the vowel ⟨o⟩ belongs to the conjunctions но ('but') or то ('then'), it is not reduced, even when unstressed.^[37]

Unstressed /u/ is generally pronounced as a lax (or near-close) [ʊ], e.g. мужчи́на [mʊˈɕːinə]^ⓘ ('man'). Between soft consonants, it becomes centralized to [ʉ̞], as in юти́ться [jʉ̞ˈtʲitsə]^ⓘ ('to huddle').

Note a spelling irregularity in /s/ of the reflexive suffix -ся: with a preceding -т- in third-person present and a -ть- in infinitive, it is pronounced as [tsə], i.e. hard instead of with its soft counterpart, since [ts], normally spelled with ⟨ц⟩, is traditionally always hard.^[38] In other forms both pronunciations [sə] and [sʲə] (or [s] and [sʲ] after vowels, spelled -сь) alternate for a speaker with some usual form-dependent preferences: in the outdated dialects, reflexive imperative verbs (such as бо́йся, lit. "be afraid yourself") may be pronounced with [sə] instead of modern (and phonetically consistent) [sʲə].^[39][40] In adverbial participles ending on -я́сь or -а́сь (with a stressed suffix), books on Russian standard pronunciation prescribe [sʲ] as the only correct variant.^[41][42]

In weakly stressed positions, vowels may become voiceless between two voiceless consonants: вы́ставка [ˈvɨstə̥fkə]^ⓘ ('exhibition'), потому́ что [pə̥tʌˈmu ʂtə]^ⓘ ('because'). This may also happen in cases where only the following consonant is voiceless: че́реп [ˈtɕerʲɪ̥p]^ⓘ ('skull').

Because of mergers of different phonemes in unstressed position, the assignment of a particular phone to a phoneme requires phonological analysis. There have been different approaches to this problem:^[43]

• The Saint Petersburg phonology school assigns allophones to particular phonemes. For example, any [ʌ] is considered as a realization of /a/.
• The Moscow phonology school uses an analysis with morphophonemes (морфоне́мы, singular морфоне́ма). It treats a given unstressed allophone as belonging to a particular morphophoneme depending on morphological alternations. For example, [ʌ] is analyzed as either |a| or |o|. To make a determination, one must seek out instances where an unstressed morpheme containing [ʌ] in one word is stressed in another word. Thus, because the word валы́ [vʌˈɫɨ] ('shafts') shows an alternation with вал [vaɫ] ('shaft'), this instance of [ʌ] belongs to the morphophoneme |a|. Meanwhile, волы́ [vʌˈɫɨ] ('oxen') alternates with вол [voɫ] ('ox'), showing that this instance of [ʌ] belongs to the morphophoneme |o|. If there are no alternations between stressed and unstressed syllables for a particular morpheme, then no assignment is made, and existence of an archiphoneme is postulated. For example, the word соба́ка [sʌˈbakə] ('dog') is analysed as |s(a/o)ˈbaka|, where |(a/o)| is an archiphoneme.^[44]
• Some linguists^[45] prefer to avoid making the decision. Their terminology includes strong vowel phonemes (the five) for stressed vowels plus several weak phonemes for unstressed vowels: thus, [ɪ] represents the weak phoneme /ɪ/, which contrasts with other weak phonemes, but not with strong ones.

Russian diphthongs all end in a non-syllabic [i̯], an allophone of /j/ and the only semivowel in Russian. In all contexts other than after a vowel, /j/ is considered an approximant consonant. Phonological descriptions of /j/ may also classify it as a consonant even in the coda. In such descriptions, Russian has no diphthongs.

The first part of diphthongs is subject to the same allophony as their constituent vowels. Examples of words with diphthongs: яйцо́ [jɪjˈtso]^ⓘ ('egg'), ей [jej]^ⓘ ('her' dat.), де́йственный [ˈdʲejstvʲɪnnɨj]^ⓘ ('effective'). /ij/, written ⟨-ий⟩ or ⟨-ый⟩, is a common inflexional affix of adjectives, participles, and nouns, where it is often unstressed; at normal conversational speed, such unstressed endings may be monophthongized to [ɪ̟].^[46] When stressed, this affix is spelled ⟨-ой⟩ and pronounced /oj/. Unstressed ⟨-ый⟩ may be pronounced [əj] (as if spelled ⟨-ой⟩) in free variation with [ɨj].^[47][48] In adjectives ending in ⟨-кий, -гий, -хий⟩, traditional Moscow norm prescribed the pronunciation [kəj, ɡəj, xəj] (as if spelled ⟨-кой, -гой, -хой⟩),^[49] but now those adjectives are usually pronounced according to the spelling, thus [kʲɪj, ɡʲɪj, xʲɪj].^[50] The same can be said about verbs ending in ⟨-кивать, -гивать, -хивать⟩.^[51]

⟨ʲ⟩ denotes palatalization, meaning the center of the tongue is raised during and after the articulation of the consonant. Phonemes that have at different times been disputed are enclosed in parentheses.

Notes

• Most consonant phonemes come in hard–soft pairs, except for always-hard /ts, ʂ, ʐ/ and always-soft /tɕ, ɕː, j/ and formerly or marginally /ʑː/. There is a marked tendency of Russian hard consonants to be velarized or uvularized,^[52][53] though this is a subject of some academic dispute.^[54][55] Velarization is clearest before the front vowels /e/ and /i/,^[56][57] and with labial and velar consonants as well as the lateral.^[58][59] As with palatalization, it results in vowel colouring and diphthongisation when stressed, in particular with /i~ɨ/, realized approximately as [ɯi̯] or [ɤ̯ɪ]. Its function is to make the contrast between hard and soft consonants perceptually more salient, and the less salient the contrast is otherwise (such as labial consonants being universally the most resistant to palatalization^[60]), the higher the velarization degree.
  • /ʐ/ and /ʂ/ are always hard in native words (even if spelling contains a "softening" letter after them, as in жена, шёлк, жить, and мышь). A few loanwords are spelled with ⟨жю⟩ or ⟨шю⟩; authoritative pronunciation dictionaries^[61] prescribe hard pronunciation for some of them (e.g. брошюра, парашют, амбушюр, шюцкор) but soft for other ones (e.g. пшют, фишю); жюри may be pronounced either way.^[62] The letter combinations ⟨жю⟩, ⟨жя⟩, ⟨жё⟩, ⟨шю⟩, ⟨шя⟩, and ⟨шё⟩ also occur in foreign proper names, mostly of French or Lithuanian origin. Notable examples include Гёльджюк (Gölcük), Жён Африк (Jeune Afrique), Жюль Верн (Jules Verne), Герхард Шюрер (Gerhard Schürer), Шяуляй (Šiauliai), and Шяшувис (Šešuvis). The dictionary of Ageenko & Zarva (1993) prescribes soft pronunciation in these names. However, since the cases of soft ⟨ж⟩ and ⟨ш⟩ are marginal and not universally pronounced as such, ⟨ж⟩ and ⟨ш⟩ are generally considered always-hard consonants, and the long phonemes /ʑː/ and /ɕː/ are not considered their soft counterparts, as they do not pattern in the same ways that other hard–soft pairs do.
  • /ts/ is generally listed among the always-hard consonants; however, certain foreign proper names, including those of Ukrainian, Polish, Lithuanian, or German origin (e.g. Цюрупа, Пацюк, Цявловский, Цюрих), as well as loanwords (e.g., хуацяо, from Chinese), contain a soft [tsʲ].^[63] The phonemicity of a soft /tsʲ/ is supported by neologisms that come from native word-building processes (e.g. фрицёнок, шпицята).^{[citation needed]} However, according to Yanushevskaya & Bunčić (2015), /ts/ really is always hard, and realizing it as palatalized [tsʲ] is considered "emphatically non-standard", and occurs only in some regional accents.^[64]
  • /tɕ/ and /j/ are always soft.
  • /ɕː/ is also always soft.^[64] A formerly common pronunciation of /ɕ/+/tɕ/^[65] indicates the sound may be two underlying phonemes: /ʂ/ and /tɕ/, thus /ɕː/ can be considered as a marginal phoneme. In today's most widespread pronunciation, [ɕtɕ] appears (instead of [ɕː]) for orthographical -зч-/-сч- where ч- starts the root of a word, and -з/-с belongs to a preposition or a "clearly distinguishable" prefix (e.g. без часо́в [bʲɪɕtɕɪˈsof]^ⓘ, 'without a clock'; расчерти́ть [rəɕtɕɪrˈtʲitʲ]^ⓘ, 'to rule'); in all other cases /ɕː/ is used (щётка [ˈɕːɵtkə]^ⓘ, гру́зчик [ˈɡruɕːɪk]^ⓘ, перепи́счик [pʲɪrʲɪˈpʲiɕːɪk], сча́стье [ˈɕːæsʲtʲjə]^ⓘ, мужчи́на [mʊˈɕːinə]^ⓘ, исщипа́ть [ɪɕːɪˈpatʲ], расщепи́ть [rəɕːɪˈpʲitʲ] etc.)
  • The marginally phonemic^[66] sound [ʑː] is largely obsolete except in the more conservative standard accent of Moscow, in which it only occurs in a handful of words. Insofar as this soft pronunciation is lost, the corresponding hard [ʐː] replaces it.^[67] This sound may derive from an underlying /zʐ/ or /sʐ/: заезжа́ть [zə(ɪ̯)ɪˈʑːætʲ], modern [zə(ɪ̯)ɪˈʐːatʲ]^ⓘ. For most speakers, it can most commonly be formed by assimilative voicing of [ɕː] (including across words): вещдо́к [vʲɪʑːˈdok]. For more information, see alveolo-palatal consonant and retroflex consonant.
• /ʂ/ and /ʐ/ are somewhat concave apical postalveolar.^[68] They may be described as retroflex, e.g. by Hamann (2004), but this is to indicate that they are not laminal nor palatalized; not to say that they are subapical.^[69] They also tend to be at least slightly labialized, including when followed by unrounded vowels.^[64][70]
• Hard /t, d, n/ are laminal denti-alveolar [t̪, d̪, n̪]; unlike in many other languages, /n/ does not become velar [ŋ] before velar consonants.^[71]
• Hard /ɫ/ has been variously described as pharyngealized apical alveolar [l̺ˤ]^[72] and velarized laminal denti-alveolar [l̪ˠ].^[55][73][74]
• Hard /r/ is postalveolar, typically a trill [r̠].^[75]
• Soft /rʲ/ is an apical dental trill [r̪ʲ], usually with only a single contact.^[75]
• Soft /tʲ, dʲ, nʲ/ are laminal alveolar [t̻͡s̻ʲ, d̻͡z̻ʲ, n̻ʲ].^[76] As of the twenty-first century /tʲ, dʲ/ are affricated in most contexts.^[77] This phenonomenon of affrication is known in Russian as tsekan'ye and dzekan'ye, and it is paralleled in Belarusian.
• Soft /lʲ/ is either laminal alveolar [l̻ʲ] or laminal denti-alveolar [l̪ʲ].^[72][78]
• /ts, s, sʲ, z, zʲ/ are dental [t̪s̪, s̪, s̪ʲ, z̪, z̪ʲ],^[79] i.e. dentalized laminal alveolar. They are pronounced with the blade of the tongue very close to the upper front teeth, with the tip of the tongue resting behind the lower front teeth.
• The voiced /v, vʲ/ are often realized with weak friction [v̞, v̞ʲ] or even as approximants [ʋ, ʋʲ], particularly in spontaneous speech.^[64]
• A marginal phoneme /ɣ/ occurs instead of /ɡ/ in certain interjections: ага́, ого́, угу́, эге, о-го-го́, э-ге-ге, гоп. (Thus, there exists a minimal pair of homographs: ага́ [ʌˈɣa]^ⓘ 'aha!' vs ага́ [ʌˈɡa]^ⓘ 'agha'). The same sound [ɣ] can be found in бухга́лтер (spelled ⟨хг⟩, though in цейхга́уз, ⟨хг⟩ is [x]), optionally in га́битус and in a few other loanwords. Also optionally (and less frequently than a century ago) [ɣ] can be used instead of [ɡ] in certain religious words (a phenomenon influenced by Church Slavonic pronunciation): Бо́га [ˈboɣə], Бо́гу [ˈboɣʊ]... (declension forms of Бог [ˈbox] 'God'), Госпо́дь [ɣʌˈspotʲ] 'Lord' (especially in the exclamation Го́споди! [ˈɣospədʲɪ] 'Oh Lord!'), благо́й [bɫʌˈɣɵj] 'good'.
• Some linguists (like I. G. Dobrodomov and his school) postulate the existence of a phonemic glottal stop /ʔ/. This marginal phoneme can be found, for example, in the word не́-а [ˈnʲeʔə]^ⓘ. Claimed minimal pairs for this phoneme include су́женный [ˈsʔuʐɨnɨj]^ⓘ 'narrowed' (a participle from су́зить 'to narrow', with prefix с- and root -уз-, cf. у́зкий 'narrow') vs су́женый [ˈsuʐɨnɨj]^ⓘ 'betrothed' (originally a participle from суди́ть 'to judge', now an adjective; the root is суд 'court') and с А́ней [ˈsʔanʲɪj]^ⓘ 'with Ann' vs Са́ней [ˈsanʲɪj]^ⓘ '(by) Alex'.^[80][81]

There is some dispute over the phonemicity of soft velar consonants. Typically, the soft–hard distinction is allophonic for velar consonants: they become soft before front vowels, as in коро́ткий [kʌˈrotkʲɪj]^ⓘ ('short'), unless there is a word boundary, in which case they are hard (e.g. к Ива́ну [k‿ɨˈvanʊ] 'to Ivan').^[82] Hard variants occur everywhere else. Exceptions are represented mostly by:

• Loanwords:
  • Soft: гёзы, гюрза́, гяу́р, секью́рити, кекс, кяри́з, са́нкхья, хянга́;
  • Hard: кок-сагы́з, гэ́льский, акы́н, кэб (кеб), хэ́ппенинг.
• Proper nouns of foreign origin:
  • Soft: Алигье́ри, Гёте, Гю́нтер, Гянджа́, Джокьяка́рта, Кёнигсберг, Кюраса́о, Кя́хта, Хью́стон, Хёндэ, Хю́бнер, Пюхяя́рви;
  • Hard: Мангышла́к, Гэ́ри, Кызылку́м, Кэмп-Дэ́вид, Архы́з, Хуанхэ́.

The rare native examples are fairly new, as most of them were coined in the last century:

• Soft: forms of the verb ткать 'weave' (ткёшь, ткёт etc., and derivatives like соткёшься); догёнок/догята, герцогёнок/герцогята; and adverbial participles of the type берегя, стерегя, стригя, жгя, пекя, секя, ткя (it is disputed whether these are part of the standard language or just informal colloquialisms)^{[citation needed]};
• Hard: the name гэ of letter ⟨г⟩, acronyms and derived words (кагебешник, днепрогэсовский), a few interjections (гы, кыш, хэй), some onomatopoeic words (гыгыкать), and colloquial forms of certain patronyms: Олегыч, Маркыч, Аристархыч (where -ыч is a contraction of standard language's patronymical suffix -ович rather than a continuation of ancient -ич).

In the mid-twentieth century, a small number of reductionist approaches made by structuralists^[83] put forth that palatalized consonants occur as the result of phonological processes involving /j/ (or palatalization as a phoneme in itself), so that there were no underlying palatalized consonants.^[84] Despite such proposals, linguists have long agreed that the underlying structure of Russian is closer to that of its acoustic properties, namely that soft consonants are separate phonemes in their own right.^[85]

Voiced consonants (/b/, /bʲ/, /d/, /dʲ/ /ɡ/, /v/, /vʲ/, /z/, /zʲ/, /ʐ/, and /ʑː/) are devoiced word-finally unless the next word begins with a voiced obstruent.^[86] In other words, their voiceless equivalent will be used (see table on the right).^[21]

Examples:

• рассказ (story, tale) sounds like расскас [rɐˈskas]
• нож (knife) sounds like нош [noʂ]
• Иванов (Ivanov) sounds like Иваноф [ɪvɐˈnof]; and so on.

Г also represents voiceless [x] word-finally in some words, such as бог [ˈbox] ('god'). This is related to the use of the marginal (or dialectal) phoneme /ɣ/ in some religious words (see Consonants).

Generally, when a voiced consonant comes before a voiceless one, its sound will shift to its voiceless equivalent (see table).^[21]

• Example: Ложка (spoon) sounds like Лошка [ˈɫoʂkə].

That happens because ж is a voiced consonant, and it comes before the voiceless к.

The same logic applies when a voiceless consonant comes before a voiced one (except в). In this case, the sound of the former will change to its voiced equivalent.^[21]

• Example: сделать (to do) sounds like зделать [ˈzʲdʲeɫətʲ].

Russian features general regressive assimilation of voicing and palatalization.^[87] In longer clusters, this means that multiple consonants may be soft despite their underlyingly (and orthographically) being hard.^[88] The process of voicing assimilation applies across word-boundaries when there is no pause between words.^[89] Within a morpheme, voicing is not distinctive before obstruents (except for /v/, and /vʲ/ when followed by a vowel or sonorant). The voicing or devoicing is determined by that of the final obstruent in the sequence:^[90] просьба [ˈprozʲbə]^ⓘ ('request'), водка [ˈvotkə]^ⓘ ('vodka'). In foreign borrowings, this isn't always the case for /f(ʲ)/, as in Адольф Гитлер [ʌˈdolʲf ˈɡʲitlʲɪr]^ⓘ ('Adolf Hitler') and граф болеет ('the count is ill'). /v/ and /vʲ/ are unusual in that they seem transparent to voicing assimilation; in the syllable onset, both voiced and voiceless consonants may appear before /v(ʲ)/:

• тварь [tvarʲ]^ⓘ) ('the creature')
• два [dva]^ⓘ ('two')
• световой [s(ʲ)vʲɪtʌˈvoj]^ⓘ ('of light')
• звезда [z(ʲ)vʲɪˈzda]^ⓘ ('star')

When /v(ʲ)/ precedes and follows obstruents, the voicing of the cluster is governed by that of the final segment (per the rule above) so that voiceless obstruents that precede /v(ʲ)/ are voiced if /v(ʲ)/ is followed by a voiced obstruent (e.g. к вдове [ɡvdʌˈvʲe] 'to the widow') while a voiceless obstruent will devoice all segments (e.g. без впуска [bʲɪs ˈfpuskə] 'without an admission').^[91]

/tɕ/, /ts/, and /x/ have voiced allophones ([dʑ], [dz] and [ɣ]) before voiced obstruents,^[86][92] as in дочь бы [ˈdodʑ bɨ]^ⓘ[93] ('a daughter would'), плацдарм [pɫʌdzˈdarm]^ⓘ ('bridge-head') and горох готов [ɡɐˈroɣ ɡɐˈtof] ('peas are ready').

Other than /mʲ/ and /nʲ/, nasals and liquids devoice between voiceless consonants or a voiceless consonant and a pause: контрфорс [ˌkontr̥ˈfors]^ⓘ) ('buttress').^[94]

Before /j/, paired consonants (that is, those that come in a hard-soft pair) are normally soft as in пью [pʲju]^ⓘ ('I drink') and бью [bʲju]^ⓘ ('I hit'). However, the last consonant of prefixes and parts of compound words generally remains hard in the standard language: отъезд [ʌˈtjest]^ⓘ ('departure'), Минюст [ˌmʲiˈnjust]^ⓘ ('Min[istry of] Just[ice]'); when the prefix ends in /s/ or /z/ there may be an optional softening: съездить [ˈs(ʲ)jezʲdʲɪtʲ]^ⓘ ('to travel').

Paired consonants preceding /e/ are also soft; although there are exceptions from loanwords, alternations across morpheme boundaries are the norm.^[95] The following examples^[96] show some of the morphological alternations between a hard consonant and its soft counterpart:

Velar consonants are soft when preceding /i/, and never occur before [ɨ] within a word.^[5]

Before hard dental consonants and /r/, labial and dental consonants are hard: орла́ [ʌrˈɫa]^ⓘ ('eagle' gen. sg), cf. орёл [ʌˈrʲoɫ] ('eagle' nom. sg).

Paired consonants preceding another consonant often inherit softness from it. This phenomenon in literary language has complicated and evolving rules with many exceptions, depending on what these consonants are, in what morphemic position they meet and to what style of speech the word belongs. In old Moscow pronunciation, softening was more widespread and regular; nowadays some cases that were once normative have become low colloquial or archaic. In fact, consonants can be softened to differing extents, become semi-hard or semi-soft.

The more similar the consonants are, the more they tend to soften each other. Also, some consonants tend to be softened less, such as labials and /r/.

Softening is stronger inside the word root and between root and suffix; it is weaker between prefix and root and weak or absent between a preposition and the word following.^[97]

• Before soft dental consonants, /lʲ/ and often soft labial consonants, dental consonants (other than /ts/) are soft.
• /x/ is assimilated to the palatalization of the following velar consonant: лёгких [ˈlʲɵxʲkʲɪx]^ⓘ) ('lungs' gen. pl.).
• Palatalization assimilation of labial consonants before labial consonants is in free variation with nonassimilation, such that бомбить ('to bomb') is either [bʌmˈbʲitʲ] or [bʌmʲˈbʲitʲ] depending on the individual speaker.
• When hard /n/ precedes its soft equivalent, it is also soft and likely to form a single long sound (see gemination). This is slightly less common across affix boundaries.

In addition to this, dental fricatives conform to the place of articulation (not just the palatalization) of following postalveolars: с частью [ˈɕːæsʲtʲjʊ]^ⓘ) ('with a part'). In careful speech, this does not occur across word boundaries.

Russian has the rare feature of nasals not typically being assimilated in place of articulation. Both /n/ and /nʲ/ appear before retroflex consonants: деньжонки [dʲɪnʲˈʐonkʲɪ]^ⓘ) ('money' (scornful)) and ханжой [xʌnˈʐoj]^ⓘ) ('sanctimonious one' instr.). In the same context, other coronal consonants are always hard.

Assimilative palatalization may sometimes also occur across word boundaries as in других гимназий [drʊˈɡʲiɣʲ ɡʲɪmˈnazʲɪj],^[64] but such pronunciation is uncommon and characteristic of uncareful speech (except in preposition+main word combinations).

As a Slavic language, Russian has fewer phonotactic restrictions on consonants than many other languages,^[98] allowing for clusters that would be difficult for English speakers; this is especially so at the beginning of a syllable, where Russian speakers make no sonority distinctions between fricatives and stops.^[99] These reduced restrictions begin at the morphological level; outside of two morphemes that contain clusters of four consonants: встрет-/встреч- 'meet' ([ˈfstrʲetʲ/ˈfstrʲetɕ]), and чёрств-/черств- 'stale' ([ˈtɕɵrstv]), native Russian morphemes have a maximum consonant cluster size of three:^[100]

For speakers who pronounce [ɕtɕ] instead of [ɕː], words like общий ('common') also constitute clusters of this type.

If /j/ is considered a consonant in the coda position, then words like айва́ ('quince') contain semivowel+consonant clusters.

Affixation also creates consonant clusters. Some prefixes, the best known being вз-/вс- ([vz-]/[fs-]), produce long word-initial clusters when they attach to a morpheme beginning with consonant(s) (e.g. |fs|+ |pɨʂkə| → вспы́шка [ˈfspɨʂkə] 'flash'). However, the four-consonant limitation persists in the syllable onset.^[101][102]

Clusters of three or more consonants are frequently simplified, usually through syncope of one of them,^[103] especially in casual pronunciation.^[104]

All word-initial four-consonant clusters begin with [vz] or [fs], followed by a stop (or, in the case of [x], a fricative), and a liquid:

Because prepositions in Russian act like clitics,^[105] the syntactic phrase composed of a preposition (most notably, the three that consist of just a single consonant: к, с, and в) and a following word constitutes a phonological word that acts like a single grammatical word.^[106] This can create a 4-consonant onset cluster not starting in [vz] or [fs]; for example, the phrase в мгнове́ние ('in an instant') is pronounced [vmɡnɐˈvʲenʲɪje].

In the syllable coda, suffixes that contain no vowels may increase the final consonant cluster of a syllable (e.g. Ноя́брьск 'city of Noyabrsk' |noˈjabrʲ|+ |sk| → [nʌˈjabrʲsk]), theoretically up to seven consonants: *мо́нстрств [ˈmonstrstf] ('of monsterships').^[107] There is usually an audible release of plosives between these consecutive consonants at word boundaries, the major exception being clusters of homorganic consonants.^[108]

Consonant cluster simplification in Russian includes degemination, syncope, dissimilation, and weak vowel insertion. For example, /sɕː/ is pronounced [ɕː], as in расще́лина ('cleft'). There are also a few isolated patterns of apparent cluster reduction (as evidenced by the mismatch between pronunciation and orthography) arguably the result of historical simplifications.^[109] For example, dental stops are dropped between a dental continuant and a dental nasal or lateral: ле́стный [ˈlʲesnɨj] 'flattering' (from ле́сть [ˈlʲesʲtʲ] 'flattery').^[110] Other examples include:

Compare: со́лнечный [ˈsoɫnʲɪt͡ɕnɨj] 'solar, sunny', серде́чный [sʲɪrˈdʲet͡ɕnɨj] 'heart (adj.), cordial', Шотла́ндия [ʂɐtˈɫanʲdʲɪjə] 'Scotland', маркси́ст [mʌrkˈsʲist] 'Marxist' (person).

The simplifications of consonant clusters are done selectively; bookish-style words and proper nouns are typically pronounced with all consonants even if they fit the pattern. For example, the word голла́ндка is pronounced in a simplified manner [ɡʌˈɫankə] for the meaning of 'Dutch oven' (a popular type of oven in Russia) and in a full form [ɡʌˈɫantkə] for 'Dutch woman' (a more exotic meaning). The orthographic combination ⟨вств⟩ is pronounced [stv] in the words здра́вствуй(те) [ˈzdrastvʊj(tʲe)] 'hello', чу́вство [ˈt͡ɕustvə] 'feeling' (does not have related words with pronounced ⟨в⟩ in the modern language, so the first ⟨в⟩ in the spelling exists only for historical reasons), безмо́лвствовать [bʲɪzˈmoɫstvəvətʲ] 'to be silent', and related words, otherwise pronounced [fstv]: баловство́ [bəɫɐfstˈvo] 'naughtiness'.

In certain cases, this syncope produces homophones, e.g. ко́стный ('bony') and ко́сный ('rigid'), both are pronounced [ˈkosnɨj]^ⓘ.

Another method of dealing with consonant clusters is inserting an epenthetic vowel (both in spelling and in pronunciation), ⟨о⟩ after most prepositions and prefixes that normally end in a hard consonant. This includes both historically motivated usage (from historical extra-short vowel ⟨ъ⟩) and cases of its modern extrapolations. There are no strict limits when the epenthetic ⟨о⟩ is obligatory, optional, or prohibited. One of the most typical cases of the epenthetic ⟨о⟩ is between a morpheme-final hard consonant and a cluster starting with the same or similar consonant. E.g. со среды́ 'from Wednesday' |s|+|srʲɪˈdɨ| → [səsrʲɪˈdɨ], not *с среды; ототру́ 'I'll scrub' |ot|+|tru| → [ʌtʌˈtru], not *оттру. The interfix ⟨о⟩ (spelled ⟨е⟩ after soft consonants) is also used in compound words: пищево́д 'oesophagus' (lit. food path) |пища|+|вод| → [pʲɪɕːɪˈvot].

Stress in Russian is phonemic and therefore unpredictable. It may fall on any syllable, and can vary drastically in similar or related words. For example, in the following table, in the numbers 50 and 60, the stress moves to the last syllable, despite having a structure similar to, say, 70 and 80:

Words can also contrast based just on stress (e.g. му́ка [ˈmukə] 'ordeal, pain, anguish' vs. мука́ [mʊˈka] 'flour, meal, farina'). Stress shifts can even occur within an inflexional paradigm: до́ма [ˈdomə] ('house' gen. sg., or 'at home') vs дома́ [dʌˈma] ('houses'). The place of the stress in a word is determined by the interplay between the morphemes it contains, as morphemes may be obligatorily stressed, obligatorily unstressed, or variably stressed.

Generally, only one syllable in a word is stressed; this rule, however, does not extend to most compound words, such as моро́зоусто́йчивый [mʌˌrozəʊˈstojtɕɪvɨj] ('frost-resistant'), which have multiple stresses, with the last of them being primary.^[111]

Phonologically, stressed syllables are mostly realised not only by the lack of aforementioned vowel reduction, but also by a somewhat longer duration than unstressed syllables. More intense pronunciation is also a relevant cue, although this quality may merge with prosodical intensity. Pitch accent has only a minimal role in indicating stress, mostly due to its prosodical importance, which may prove a difficulty for Russians identifying stressed syllables in more pitched languages.^[112]

A stress defines a phonological concept of phonetic word — a sequence of morphemes clustered around one nuclear stress. A phonetic word may contain multiple lexical items.^[113]

There are numerous ways in which Russian spelling does not match pronunciation. The historical transformation of /ɡ/ into /v/ in genitive case endings and the word for 'him' is not reflected in the modern Russian orthography: the pronoun его [jɪˈvo] 'his/him', and the adjectival declension suffixes -ого and -его. Orthographic г represents /x/ in a handful of word roots: легк-/лёгк-/легч- 'easy' and мягк-/мягч- 'soft'. There are a handful of words in which consonants which have long since ceased to be pronounced even in careful pronunciation are still spelled, e.g., the 'l' in солнце [ˈsontsɨ] ('sun').

Between any vowel and /i/ (excluding instances across affix boundaries but including unstressed vowels that have merged with /i/), /j/ may be dropped: аист [ˈa.ɪst] ('stork') and делает [ˈdʲeɫəɪt] ('does').^[114] (Halle (1959) cites заезжать and other instances of intervening prefix and preposition boundaries as exceptions to this tendency.)

/i/ velarizes hard consonants: ты [tˠɨ]^ⓘ ('you' sing.). /o/ and /u/ velarize and labialize hard consonants and labialize soft consonants: бок [bˠʷok]^ⓘ ('side'), нёс [nʲʷɵs]^ⓘ ('(he) carried').^[115] /o/ is a diphthong [ʊ̯o] or even a triphthong [ʊ̯ɔʌ̯], with a closer lip rounding at the beginning of the vowel that gets progressively weaker, particularly when occurring word-initially or word-finally under stress.^[116]

A weak palatal offglide may occur between certain soft consonants and back vowels (e.g. ляжка 'thigh' [ˈlʲi̯aʂkə]).^[117]

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