Quick answer
Voiced consonants go voiceless at the end of a word and before a voiceless consonant. Voiceless ones go voiced before a voiced one.
The pairs
| Voiced | Voiceless | Example |
|---|---|---|
| б | п | хлеб → “khlep” |
| в | ф | Че́хов → “Chekhof” |
| г | к | друг → “drook” |
| д | т | го́род → “górat” |
| ж | ш | нож → “nosh” |
| з | с | раз → “ras” |
The spelling never changes, because the related forms need the original letter: хлеб — хле́ба, го́род — го́рода, where the voiced consonant is clearly audible again.
Three rules
One: at the end of a word, voiced becomes voiceless. Клуб is “klup”. Two: before a voiceless consonant, the same. Во́дка is “vótka”. Three: before a voiced consonant, voiceless becomes voiced. Сде́лать is “zdélat”, вокза́л is “vagzál”.
The ones worth memorising
Сего́дня is “sevódnya” — the г becomes в. Adjective endings -ого / -его do the same: но́вого is “nóvava”. Что is “shto” and коне́чно is “konéshna” — those two are pure exceptions, not assimilation.
Why bother?
Because you will not recognise words you know. A learner listening for “Chekhov” will miss Че́хов entirely. Reading the spelling and hearing the sound are two different skills, and this page is the bridge.
Typical mistakes
Reading хлеб with a clear b
“khlep”
Final voiced consonants devoice.
Reading сде́лать as “sdelat”
“zdélat”
с before д becomes voiced.
Check yourself
How is сде́лать pronounced?