In the pronunciation of the Russian language, several ways of vowel reduction (and its absence) are distinguished between the standard language and dialects. Russian orthography most often does not reflect vowel reduction, which can confuse foreign-language learners, but some spelling reforms have changed some words. There are five vowel phonemes in Standard Russian. Vowels tend to merge when they are unstressed. The vowels and have the same unstressed allophones for a number of dialects and reduce to an unclear schwa. Unstressed may become more central and merge with. Under some circumstances,, , and may all merge. The fifth vowel,, may also be centralized but does not typically merge with any of the other vowels. Other types of reduction are phonetic, such as that of the high vowels ( and ), which become near-close. Thus, игра́ть ('to play') is pronounced, and мужчи́на ('man') is pronounced.

General description

The five Russian vowels in unstressed position show two levels of reduction: The allophonic result of the reduction is also heavily dependent on the quality or the nonexistence of the preceding consonant. Thus, the reduction is further grouped into three types according to the environment: The unstressed vowels also may be grouped in series that reflect similar patterns of reduction:

High vowels

Two high vowels and are usually thought to undergo no reduction. However, on the phonetic level, they show allophonic centralization, particularly under the influence of preceding or following consonants. The unstressed high back vowel is either (after hard consonants, written ) or (after soft consonants, written, except , ). The unstressed high front vowel is either or (after soft consonants, written ) or or (after hard consonants, written, except , ). Nevertheless, in rapid colloquial speech they both may be reduced to schwa, for example, до́брым ('kind', instrumental case, singular masculine neuter) versus до́бром ('kind', prepositional case, singular masculine neuter). The case ending //-im// in the former case may surface as like the case ending //-om//, which thus leads to the merger of and, or as де́лают ('they do') versus де́лает ('he/it does'). Both may surface as or.

Back vowels

Other than in Northern Russian dialects, Russian-speakers have a strong tendency to merge unstressed and. The phenomenon is called akanye (аканье), and some scholars postulate an early tendency towards it in the earliest known textual evidence of confusion between written "a" and "o" in a manuscript that was copied in Moscow in 1339. Akanye contrasts with okanye (оканье) pronunciations in Standard Russian as follows: Across certain word-final suffixes, the reductions do not completely apply. In certain suffixes, after palatalised consonants and, and (which is written as ⟨е⟩) can be distinguished from and from each other: по́ле ('field' nominative singular neuter) is different from по́ля ('field' singular genitive), and the final sounds differ from the realisation of in that position. There are a number of exceptions to the above comments regarding the akanye:

Front vowels

The main feature of front vowel reduction is ikanye (иканье), the merger of unstressed with. Because has several allophones (depending on both stress and proximity to palatalised consonants), unstressed is pronounced as one of those allophones, rather than the close front unrounded vowel. For example, семена́ ('seeds') is pronounced and цена́ as ('price'). In registers without the merger (yekanye or еканье), unstressed is more retracted. Even then, however, the distinction between unstressed and unstressed is most clearly heard in the syllable immediately before the stress. Thus, прида́ть ('to add to') contrasts with преда́ть ('to betray'). Both are pronounced and respectively. The yekanye pronunciation is coupled with a stronger tendency for both unstressed and, which are pronounced the same as. Speakers may switch between both pronunciations because of various factors, the most important factor likely being the speed of pronunciation.

Yakanye

Yakanye (яканье) is the pronunciation of unstressed and after palatalised consonants preceding a stressed syllable as, rather than (несли́ is pronounced , not ). This pronunciation is observed in Belarusian and in most Southern Russian dialects, as is expressed in a quip (with liberal yakanye): !Orthography !Standard pronunciation !Yakanye pronunciation !Translation That example also demonstrates other features of Southern dialects: palatalised final in the third-person forms of verbs, for and for (in some places) and, clear unstressed for or.

Spelling

Generally, vowel reduction is not reflected in the Russian spelling. However, in some words, the spelling has been changed based on vowel reduction and so some words are spelled despite their etymology: Spelling those words with ⟨а⟩ was already common in the 18th century, but it co-existed with the spelling with ⟨о⟩, conforming to etymology of those words. Dictionaries often gave both spellings. In the second half of the 19th century, Yakov Grot recommended spelling those words with ⟨о⟩ (conforming to their etymology), but his recommendations were not followed by all editors. The Ushakov Dictionary (1935–1940) gives паро́м, корова́й and карава́й. Finally the spelling of those words with ⟨а⟩ was set by the 1956 orthographic codification (orthographic rules and spelling dictionary). That is, in cases of doubt, codifiers of 1956 based their choice not on etymological conformity but on the spread of usage. That spelling has a long history and is based on a folk etymology basing the word on ви́деть (to see,) instead of ве́дать (to know). In the closely related Belarusian, the original has merged with, like in Standard Russian, but the reduced pronunciation is reflected in the spelling.