Is DH not pronounced like D? GH like a hard G? Or can I just blame the British, the way I blame the Portuguese for weird spellings of Chinese words?
ETA: I suppose the KH comes from trying to keep the Khans and Kahns straight. 
And what’s up with usernames with silent e’s at the end? Huh?
I haven’t checked on the details, but it’s almost certainly because dh, gh and kh are not the same sound as d, g and k. just as sh and s are different sounds in English.
probably because English doesn’t have any way to represent the sounds in those languages, and we transliterate it as best we can. kind of like how we can represent a Japanese name like “Ito” as either Ito or Itoh. Or with German names/words; we have no equivalent for ö so we transliterate a name like “Göthe” as “Goethe.”
They’re aspirated consonants. They don’t particularly matter in English, but in some languages they’re absolutely essential in differentiating words.
Another common combination is BH. My doctor’s name begins with Bha… for example.
As far as I can figure, it’s just pronounced like a B.
What does it mean that a consonant is “aspirated”? And how does that affect the sound of, e.g., bh, gh, dh, kh?
You put a little puff of air when pronouncing the consonant. In English, you can hear it most distinctly at the ends of words:
ship-puh
road-duh
bet-tuh
Aspirated and unaspirated consonants appear in standard American and British English, but because they don’t change the meaning of a word, it’s very difficult to get monolingual English speakers to hear the difference.
And if they do hear a difference, it’s usually the wrong difference. For example, kan (“ear”) and khan (a family name or feudal title) are two different words in Bengali. However, an English speaker might hear them as gan and kan. Well, gan (“song”) is also a different word.
Suffice to say, in South Asian languages, putting an “H” after a plosive consonant changes the consonant in a way that changes the meaning of a word. It’s hard to explain in text, and even if we were face-to-face, and you could hear me, it still might take a long while before you got it.
And this kind of thing is true for any set of sounds that aren’t important to distinguishing meaning in a specific language. For example, many Arabic speakers can’t distinguish between p and b, because there is no difference in their language.
Most South Asian languages have this set of plosive consonants:
k kʰ g gʰ
tʃ tʃʰ dʒ dʒʰ
ʈ ʈʰ ɖ ɖʰ
t̯ t̯ʰ d̯ d̯ʰ
p pʰ b bʰ
Standard English speakers generally are only going to be able to hear them as:
k/g k g g
tʃ/dʒ tʃ dʒ dʒ
t/d t d d
t/d t d d
p/b p b b
I do believe you got that backwards. In English, the p/t/k consonant sounds are aspirated at the beginning of syllables, but not at the end.
Well, English speakers tend do something to the terminal consonant when pronouncing Tagalog words like sandok and ilog. That extra whatever-it-is isn’t exactly incorrect but it sounds very, very odd.
“Wh” is a good example of this that may be familiar to English speakers - eg, the difference between “where” and “wear”.
I have heard some accents (eg Scottish) pronounce the former with an obvious blow of air on the “wh” - my own native accent would treat them as homophones.
I don’t know a word of Vietnamese but same thing in that language - the names are usually written as “Vinh”, “Tranh” etc, in English.
Bad example, as Goethe is spelled Goethe in German. But umlauts can be tricky. What do you do with letters like Ø ?
In Vietnamese, those examples are not for aspiration. The “nh” at the end is either pronounced “n” or “ng”, generally, depending on what part of the country the speaker hails. Wikipedia has a good description of the Vietnamese alphabet here.
I am a native English English speaker and this makes no sense to me at all.
Not really. For speakers who differentiate between “where” and “wear”, the difference is not one of aspiration. You can test this yourself by holding your hand up to your mouth and saying both words. In both cases you’ll notice airflow when pronouncing the initial consonant.
That’s not the same difference, though.
The classic example is “stop” and “top”—the two Ts have different sounds. “Stop” has an unaspirated T, and “top” has an aspirated T. Hold your hand in front of your mouth when saying them and you can feel the difference. Work at it until you can hear the difference.
That said, the gh in Afghanistan isn’t an aspirated g, but the sound /γ/. I believe the kh in Khan is /x/. H often gets used to modify letters, as in English wh /ʍ/ and sh /∫/ and th /θ/. The dh in Gandhi is aspirated d, though. Basically, if English is your first language, your dh is fine but you’d have trouble saying Gandi.
For some of his examples, it will make sense if you imagine yourself pronouncing the words emphatically. For example, if someone asks, “Did you say ‘bed’ or ‘bet’?”, you might answer “Bet!” with a very pronounced aspiration, in order to emphasize the difference. You wouldn’t normally aspirate the /t/ at the end of a word, though, and contrary to what Terminus Est claims, you would probably never aspirate a /d/, even if it occurred at the beginning of a word.
Too-late-to-edit: psychonaut is right; strike the last sentence of my previous post.
It depends on what language, specifically, you’re speaking. Throughout much of South Asia, “khan” is pronounced with an aspirated K sound. Certainly all the Indian actors named “Khan,” you would rarely hear people referring to them with the /x/ pronunciation in most of India.