No, you have that right. But while that is analogous to whispering/shouting it is not, in fact, whispering or shouting. etv78 is correct, ASL can’t be whispered.
While not a native Mandarin speaker, I can understand whispered Mandarin just fine. My Chinese family have no issue with understanding whispering in either Mandarin, Shanghaiese. The Hubei branch of the family might but I’m not sure because I’ve never heard them speak at anything below a bellow. 
English. Actors in TV shows and movies need to learn how to stage whisper
We called it either Telephone or Gossip.
Telephone here. American.
I just did some test whispering in Vietnamese and I had a very hard time applying the tones, but even so I suspect that whatever is whispered would still be understood from situational context.
Likewise a lot of my VN friends don’t apply the tonal marks when they text or comment on Facebook, but they can still be understood from the context.
Whisper Down the Lane. American, Middle Atlantic states.
Damn the phone signal must suck in your country.
That game is called Telephone here in Canada too. I suspect it was once called something else, but they teach it to very young children in ultra-PC environments here as a setup to any of various moral lessons (think “there are two sides to every story” or “don’t believe everything you hear”, for example) and so had to remove any reference to languages/nationalities.
For a while, “Chinese” anything was used to denote a version more complex than the original- whether because the the language is supposed to be very hard to learn for English speakers or because Chinese checkers is damn hard, I don’t know.
I played it first in elementary school. My teacher called it “Grapevine”. Later on, I’ve heard it called Telephone or Party Line.
This word has been “Grapped” by myself, The Grapevinest.
Perhaps that’s why modern english has seemed to dominate the western world? It’s survived natural selection towards an advantage in whispering.
Apparently we must tell a lot of secrets.
I don’t know about other languages, but, in English, we get around this because nearly all unvoiced consonants are aspirated, while unvoiced ones never are. Thus, even when whispering, there’s still a difference.
The ones that can’t be aspirated tend to have the voiced version be softer or shorter, like a whispered /z/ vs a whispered /s/. And the few consonant positions that are not usually aspirated have no phonemic difference between the voiced and unvoiced versions: if you say “sdop” for “stop,” it may sound a bit funny, but people still recognize it as the same word.
Good point. This suggests that languages like Hindi which include some aspirated/unaspirated minimal pairs (that are not voiced/unvoiced contrasting as well) might be a little more ambiguous than English when whispered.
(American here) we also played that game back in grade school, and we called it Telephone Purple Monkey Dishwasher.
Fortran?
nope.Sorry,not true. It doesn’t matter if you whisper in Fortran.
Because Fortran is always incomprehensible–whether written, spoken, or whispered.
It’s (or at least was when I was a kid) popular here in Finland too. We call it the broken phone 
I’d like to nominate Central Rotokas, whose consonant inventory is small and distinguished only on two dimensions: voicing and place of articulation. There are only six phonemes, comprised of three voiced/unvoiced pairs. Whispering is therefore has the potential to introduce a lot of ambiguity (relative to, say, any other language discussed in this thread so far). Then again, I’m not an expert on Rotokas, so it’s possible that, as with English, there are non-phonemic differences between the voiced and unvoiced pairs which would serve to distinguish them in whispered speech.
Cool, psychonaut – good sleuthing! I think this answers the OP as well as can be hoped for.