People crying in sadness vs crying out in anger, I know there's some gray area in between where they can be used interchangeably, it's hard to get

The primary emotion is quite important, you generally wouldn't exchange the two unless you intended to express a sense of some sort of emotive confusion in the character. As a metaphor, crying in sadness is kind of like a rhythmical peppering, like rain, or being pat on the back rhythmically, whereas crying in anger would be like somebody hitting you with a fire hose and knocking you off your feet, it is powerful. It is not actual crying, the word is being used in it's secondary sense of "loud noise".

"shriek" and "ream" are both words that seem to imply emotion more than any specific sound. Is that right?

The only ream I know if is a sex act. Shrieking does imply emotion, but through a specific sound, so it is very sound oriented. It is a piercing sound, it get's your attention. Human beings are keyed to it, it will cause your eyes to widen in apprehension almost immediately. It is the sound of danger, or death. To use another water methaphor, a shriek is like a very thin and powerful stream hitting you dead in the forehead while spiders crawl up your back.

Can any sound be described as "piercing" if it's loud and annoying? Like thunder for example.

Not any. Piercing is pitch related, which to use a visual comparison is like the brightness of a colour. You said in your AMA you can feel the music (bass notes etc), that is the dark brown of the sound world. Piercing sounds are at the complete opposite end, so bright and shiny it hurts your eyes to look. Like looking at the sun.

apparently people use "ejaculates" as a dialogue tag?!?! It seems to mean "to say suddenly or without warning" (or does it just mean "interrupt"?), but the more normal use of "ejaculates" doesn't imply that at all. I don't know if this is a deaf thing or maybe I'm just dense. Does sound have something to do with this?

Literary ejaculation is a direct relative of sexual ejaculation. It means a short, quick, perhaps unexpected outburst ;)

What does "jive" mean? Does "he speaks jive" and "he speaks AAVE" and "he speaks Ebonics" all refer to the same thing? I was raised by black parents but I can't understand any dialogue written in black dialect. I know not all black people talk like that but is there a way to mark that in a novel? Do you know of a webpage that would tell me how to translate dialogue into dialect like that?

Um..jive..it varies. In common usage it would mean deception, nonsense or worthlessness. Maybe in the US is has more use, but it's a rarely used word. "He speaks jive" would typically means he talks rubbish and not worth listening/talking to. We all know someone like that. AAVE (had to google that) and ebonics are the same. I wouldn't rely on a webpage, ebonics, like vernacular in general, changes often. You would do better speaking to a black person who uses it. Because it isn't a "written" language it relies very much on word of mouth.

Are "stammer" and "stutter" synonymous?

Yes. Stammer is more "British English" and stutter more "American". Stuttering is often associated with repeating the first syllable, but there is so little difference it is not worth separating.

What about "chat"? Dictionary says "to speak informally" but I feel like it implies something I'm not getting. Is it speaking fast? Can you use "chat" as a dialogue tag? (like "What are you doing tonight?' he chatted"), I don't think I've seen it but the dictionary makes it sound like you can.

Informal. That's about as accurate as you can get. Just any casual conversation is a "chat". It wouldn't work as a dialogue tag at all. "We chatted all evening" would be fine. There is a related word though, "chattered" which is to talk about trivialities with speed. It tends to indicate nervousness. Also known as rambling.

"mumbling" sometimes implies apathy but other times hostility. Is that right? That's weird because it connotes opposites. What does it sound like? Is it synonymous with whispering?

It can mean both. In the apathetic sense you are mumbling because you can't be bothered to make the effort to talk properly, in hostility you are mumbling in an effort to disguise your words. It's a form of passive-aggressive hostility. You want to cuss them out, but you are afraid to say it out loud for fear of repercussions.

I know cats "meow", dogs "bark" and cows "moo" but what does these words mean when used in other contexts? Sometimes other animals are described with the same sounds, like I think foxes bark which makes sense because they're like dogs but I think I've heard dolphins described as barking too. That's weird. Does a dolphin and a dog really make the same sound? _

Ok there are some differences here...

"Meow" is an onomatopoeic word. This will be tough. Onomatopoeia is when a word is spelled how it sounds, which will be a difficult concept to translate. The same goes for "moo". Barking however is different ("woof" is the onomatopoeic version). A bark is any short sharp sound. Humans can bark too, such as "he barked orders at them". It indicates a lack of patience and civility, anger perhaps. The best I can do regarding onomatopoeia in a fashion you will understand is to suggest (or remember) standing in front of a set of speakers at a club with a heavy and rhythmical bass kick. You have said already you can feel it, and anyone who has been in a loud club is familiar with the wall of pressure that goes right through your torso when the bass is too loud. Basically if you broke that pressure wave into a beginning, middle and end, the start of the pressure what sounds almost exactly like the letter "B", while the centre sounds like "OO" and the trail end of the sounds imitates the letter "M", which results in "BOOM", which is also an onomatopoeic word.

"howl" is just for animals except "howling in pain" right? Is a dog's howl just a long bark or does it sound different? Do different dogs sound different? What if they're the same size and breed?

Nah not just animals or pain. It is a type of sound. A long drawn out sound. Symbolic of anguish in humans, could also signify wildness, like a mad person. A howl and a bark are quite different in terms of sound. A bark is short and sharp, it rises quickly and falls as quick. A howl starts quite high and rolls off slowly over time in a gentle arc. A bark is more like being struck with a fist, a howl is more like being squeezed slowly. It's like the difference between < and (, if you imagined them as graphs on their side.

"Chirp" and "squawk" were originally animal noises but are now used in other contexts right? I don't know what they mean really. Birds and mice do them both interchangeably, that's as specific as I know. And I think bats chirp but never squawk? Is there a chart somewhere showing which animals make which sounds? Like, can a weasel growl? What about bears? Bears look like the kind of animal that should "growl" but I feel like I've never seen that written and Google doesn't show a lot of usage.

They are animal noises, but like bark, can also be used to indicate a method of talking in people. Mice would probably be said to squeak rather than squawk, which is a difference only a hearing person can understand. They sound different. This is another example of onomatopoeia. A squeak is shorter, generally quieter too, in reference to human is synonymous with whisper. A squawk is a loud sound, in humans synonymous with shout, often used in reference to women to denote a high pitch and lack of emotional control. Growl is menacing, and so bears would be an appropriate usage.

Do all doors creak? Can all doors be slammed? Windows? Does "slam" always imply loudness? Do you always slam doors when you're mad? Do deaf people slam doors when they're mad? (I don't think so, but if it's just a function of being mad I might do it and not notice because I'm mad). People say "he slammed that beer" to mean chugged, that's silent right? Or does it mean "gurgle" in that sense?

No not all doors. Only if they haven't been taken care of. Slam (in regards to sound) is a loud, short sharp sound. Kind of like bark earlier. But it is low pitched. This is important. Otherwise "smashed" is likely more appropriate.

"Gurgle" is another hard one. And "gargle", that means something different right?

They are different, but related. Gargling is an action that creates gurgling. In language it would generally indicate difficulty talking, usually due to liquid in the mouth or throat.