The cases where "о" is pronounced as "a"

Question

I'm working on Russian pronunciation and I have come across a couple of words containing letter о.

• зовут is pronounced as zavut
• хорошая is pronounced as xaroshaya

There are lots of such words where о pronounced as a.

Is there a grammatical/phonetical rule for this pronunciation?

Edit: Thanks for the great answers, I have concluded that deriving a definite rule for this feature is not feasible and I have found a nice CMU pronunciation dictionary also correctly containing words related with this reduction: https://sourceforge.net/projects/cmusphinx/files/Acoustic%20and%20Language%20Models/Russian/

Answer 1

You could probably work something out from etymology, but generally speaking no, except this can only happen for unstressed vowels. Russian spelling is mostly morphological, so a good rule of thumb for stem vowels is to try and find a word that has the vowel in question stressed, though this isn’t always possible. For prefixes and suffixes you’ll just have to remember a list.

The reason for the confusing spelling is that the vowel that confuses you isn’t [a] or [o] but [ɐ]^what? or maybe even the familliar English [ə],^what? and vowel phonemes /a/ and /o/ both produce that sound when they undergo reduction in an unstressed position after a hard consonant. This can happen a bit differently in different places: for example, in downtown Moscow you’re more likely to hear a well-articulated [ɐ], whereas moving to the suburbs just 30 kilometers away will get you a much shorter, almost unpronounced sound. Russian speakers usually perceive this as Muscovites emphasising the ah sound, hence аканье “ah-ing”, but the reality is that the sound is always the same, it’s just that the reduction in Moscow is not that strong. Furthermore, in Northern European Russia (the stereotypical example being the city of Vologda) the merger is in fact absent and an unstressed /o/ still sounds oh-ish, hence оканье “oh-ing”. (I hear that the schoolchildren there are quite amused by textbooks that teach them to avoid a spelling mistake that’s impossible to make in their dialect.)

Finally, there’s always Belarusian, which is rather close to Russian, but has its spelling organized completely differently, so you can always spell ⟨а⟩ for unstressed /a/~/o/ there :)

Answer 2

General rule is that unstressed о is pronounced as а. In my perception though it's not exactly а but something in between.

Answer 3

I presume you really care about how Russian “о” is pronounced, not how it’s spelled in English transliteration (which isn’t fixed, but varies depending on who’s doing the transliteration; it looks like you’re using a transliteration that tries to mimic the variation in pronunciation of “о”, which is a bit unusual). Briefly, the way to work out how “о” is pronounced in a given Russian word is:

1. You need to know which syllable of the word is stressed. This often can’t be worked out from spelling (although there are plenty of patterns that can help guess it) — it pretty much has to be learned for each word. Some textbooks helpfully mark it with an accent, like “молоко́”, but it’s not usually shown in writing at all.

2. When “о” is in the stressed syllable (eg “дом”), it’s the main Russian “о” sound, [o] in IPA (International Phonetic Alphabet).

3. When “о” is in the syllable directly before the stress (eg “зовут”), it’s pronounced with a short Russian “а” sound, [a] in IPA.

4. When “о” is anywhere else in the word, it’s a reduced vowel, [ə] — roughly the vowel of English un-emphasised “the”, as in “the cat sat on the mat”, sometimes written in English as uh.

If you listen to the pronunciations of “хорошо́” and “молоко́” on Forvo, you’ll hear the three different pronunciations of “о” in succession.

This is the main rule of thumb to use for learners; Alex Sphilkin’s answer gives good more detailed background about variation between different Russian accents/dialects.

Answer 4

If here spelling means what it usually means, i.e. orthography, mostly we spell o and pronounce a in unstressed positions.

It is spelled молоко and said [малако], it's simple.

As for the rules of writing, we mostly preserve the stem vowels. We can check them knowing other words with the same stem, where the o is stressed.

If there are no such words, then we have just to remember there is o written.

Молоко - the second o is checked by the word молочный, and the first o is to be memorized.

фотография is a borrowing, we cannot check the vowels (but for фото), but we preserve the o-s. And there is no [o] in pronunciation, because the stress is on a.