The Russian language includes 10 vowel sounds which can be divided into 5 rhyme pairs. Each pair consists of one vowel and its iotated version (except ы—и pair). By this I mean we add the sound “i” before the vowel to get a iotated version.
Knowing that will help you remember the vowels.
Rule # 1. Letter «o» sometimes sounds like [a]
The letter “o” can be pronounced in two different ways:
1. like [o], if it is the stressed position. For example, «дом» (house)
2. like a very short [a] in the unstressed position. For example «Россия» (Russia)
Of course, it is not a mistake if you pronounce “o” like [o] in either position. And you will be understood. And some regions of Russia do pronounce it in this way. But the reason why you should know it is that people in central part of Russia (Moscow, Saint-Petersburg and other) pronounce unstressed “o” like [a]. So without knowing it you might be confused when you start talking with them.
For example, the Russian word “хорошо” (which means “good”) has the last vowel “o” stressed. So that means the last “o” sounds like [o] and the rest o’s sound like [a]. And this is why you will hear from radio [harasho] instead of [horosho].
There is not a rule which syllable is stressed, you just have to learn how the word is pronounced when you learn it. In this course to show you the stress in new words I use the bold letter, like that “хорошо”.
I will add more rules later :)