Can you train the dictation?

I think I found it! In iOS 10, go to settings – General – accessibility – speech – pronunciations. Type in the new word and then press the microphone button. Say the word using correct pronunciation. You'll be presented with different pronunciation options and just select the one that sounds the most correct. I did this for a couple of family names that are unusual, mostly because of having Spanish pronunciations, and voice dictation recognized them immediately afterward.

You can correct the misspelling by double-tapping on the incorrectly recognized word to get a list of suggestions. Perhaps the spelling you want is on the list. I don't know whether iOS watches your corrections and learns to add them to suggestion lists.

See also this thread: https://discussions.apple.com/thread/3816914?answerId=17924635022#17924635022

You’ll have to expect that with odd words like that. But I am getting common English words interpreted as if I have a strong southern US accent, even though I am from the upper Midwest. I tried changing my settings to English/Canadian too... no difference.

Oh it also turns fairly common words into oddly spelled proper names. Spawn became Spohn. And it cannot tell from context which homophone to use. It was actually pretty good about that up until a year or so ago.

Maybe I should just try using a southern accent and see if it understands better??

Not there in "Enhanced Dictation" installed on my Mac which doesn't go through the Cloud.

I could not get it to recognise "ransomware" when I was dictating wordage from a set of online sides to Word on my Mac -- it came up with a variety of phrases which had me falling about laughing. I resorted to saying "ransom" and typing the rest. Strange names for malware etc didn't compute either though funnily enough it managed a few acronyms without hesitation. I haven't found a way to add words to the desktop version - one can only hope Apple is updating in the background and improving. But overall it's pretty good and is doing well with my Eng/Aus accent. Will take on board the tip I read somewhere here about using iPhone headphones.

No, you can't train it to recognize new words, but you can teach it new associations wrt your contacts.

See here:

https://discussions.apple.com/thread/3392567?start=0&tstart=0