To whom it may be interesting:
I think the problem what Robert tried to describe was the difference in pronunciation of English and Russian voiced consonants. For example, compare English "book", "dull", "goal" with similarly (but not eqaully!) sounding Russian "бук", "дал", "гол". The initial consonants in English and Russian examples do not fully coincide.
If someone is interested in technical details, let me drop some light on it.
"Voiced" can be understood differently in different languages. In real world, there is a continuous spectrum of "voicing degrees".
Below is some theoretical background:
If the vocal chords vibrate during the entire occlusion time of a consonant, the consonant is
"fully voiced". If they vibrate during only a part of the consonant occlusion time, the consonant is
"partially voiced". If they do not vibrate during the consonant occlusion, but start vibrating immediately after the consonant release (when a consonant is followed by a vowel), it is a
"tenuis voiceless consonant". If they do not vibrate during the consonant occlusion, and do not start vibrating immediately after its release, but there is a noticeable delay between a consonant and a subsequent vowel, it is an
"aspirated voiceless consonant". There can also be different degrees of partial voicing, as well as different degrees of aspiration.
Wikipedia provides more details on this phenomenon:
Voice onset time - Wikipedia, the free encyclopedia.
In Russian, voiced stops (б, д, г) are always "fully voiced". For example, when we pronounce "бар", the vocal chords start vibrating at the very moment the lips come in touch in order to make an occlusion, they continue vibrating during all the occlusion time producing the voice, and the voice continues throughout the consonant release and the subsequent vowel articulation. In addition, the voicing is more intense as compared to the English pronunciation, but the muscle tension is weaker, so this degree of voicing reminds the one of a vowel: voicing somewhat "prevails" over the consonant noise.
The voiced stops in English (b, d, g) more or less remind Russian ones only when they happen inter-vocalically (i.e between two vowels) as in "aBout", "aDapt", "aGo". Word-initially and word-finally they are only "partially voiced" or they can even be "voiceless tenuis". Word-initially, voicing extends over the final part of a consonant (the moment of its release): "bell", "dime", "gun". The word final position (as in "rub", "had", "frog") is even more complicated, it is discussed in the following article: Fortis and lenis - Wikipedia, the free encyclopedia.
Quotation: "Word-initially, the contrast has more to do with aspiration; /t/ is aspirated and /d/ is an unaspirated voiceless stop. In the syllable coda, however, /t/ is instead pronounced with glottalization, unrelease, and a shorter vowel while /d/ remains voiceless. In this way, the terms fortis and lenis are convenient in discussing English phonology, even if they are phonetically imprecise."
So, in English voice is not the main distinctive feature for "p-b", "t-d", "k-g". In Russian, it is the voice which is the only distinctive feature between them.
Word-initially, English contrasts "voiceless aspirated" with "partially voiced" (or even "voiceless tenuis") consonants (as in "park" – "bark", "time – dime", "coat" – "goat"). Russian contrasts "voiceless tenuis" with "fully voiced" consonants (as in "пар" – "бар", "том" – "дом", "кот" – "год").
The distinction used in English is similar to the one in other Germanic languages (e.g German, Swedish). It is also similar in Chinese and Korean.
The distinction used in Russian is similar to the one in other Slavic languages, in Romance languages (like Spanish, French etc.). It is also similar in Japanese.
This difference creates potential problems for both Russians learning English and for native English speakers who learn Russian.
Russians are not used to aspiration, and they can pronounce "park", "time", "coat" with Russian unaspirated (tenuis) consonants. In this case, those words might seem sound similar to "bark", "dime", "goat" to native English speakers. English speakers may fail to recognise a consonant as "voiceless" if it is not supplied with sufficient aspiration, so they can deduct "Russians are unable to produce voiceless consonants", but Russians would certainly disagree: "the consonants I pronounce ARE voiceless".
Native speakers of English are not used to fully voiced consonants word-initially, and they can pronounce "бар", "дом", "год" with English partially voiced consonants. In this case, those words might seem sound similar to "пар", "том", "кот" to native Russian speakers. Russians may fail to recognise a consonant as "voiced" if it is not fully voiced, so they can deduct "English speakers are unable to produce voiced consonants, at least word-initially", but English speakers would disagree: "the consonants I pronounce ARE voiced".
I think what Robert mistakenly called "aspiration" of English voiced consonants is this very difference between English and Russian voiced consonants (partially voiced VS fully voiced).