Dictating to text is one of the great things that macOS gave us a few years ago. In both Mojave and Catalina, you enable dictation in System Preferences in the Keyboard > Dictation Pane.
I use the “double-command” shortcut to enable dictation but I also find it helpful to set up the Mac version of “Hey Siri”. To start, hop over to Accessibility > Dictation (Mojave) or Accessibility > Voice Control (Catalina) to extend your interaction. Enable dictation or voice control, as supplied. On Catalina, you may need to download additional elements which takes a moment or two.
In Mojave, you can set a dictation keyword. I go with “Computer”, because it sounds very Scotty from Star Trek TOS. I prefer to enable sound feedback so I know when my command has been picked up properly.
To ask Siri about the weather, I say, “Computer. <beat> Open Siri. <wait for tone> What is the weather for today?”. There’s a definite pause needed after “Computer”.
Catalina offers an always-on version when you enable voice control.
This little control panel lets you sleep or wake your mike:
Once in place, you can say “Open Siri”. Confirm that you want to enable Ask Siri and you know that employees or contractors somewhere — I believe it was Ireland — will be laughing at you, but privacy is an illusion these days. Search for articles similar to “Apple Resumes Human Reviews of Siri Audio With iOS 13.2 Update” for more details. As with Mojave, you’ll need to develop separate dialects for iOS and Mac for controlling your system, with significant pauses to let the OS catch up with you.
Always-on dictation seems to send my MBP into windtunnel spasms, so you may want to use those keyboard shortcuts instead.
Once on, you can request “What can I say” and a list of commands pops up. It’s pretty basic and uninspiring as a support doc goes but it’s a start and the commands are quite extensive.
For example, say “Open TextEdit <pause> New item (assuming you don’t have TextEdit setup to create one on launch).”
Next, try dictating. I recommend opening a browser tab apart from TextEdit and just speak from a reference document. For example:
Listen my children and you shall hear
Of the midnight ride of Paul Revere,
On the eighteenth of April, in Seventy-five;
Hardly a man is now alive
Who remembers that famous day and year.
You’ll immediately see some of the weaknesses involved in dictation.
Starting over, I’ve used some dictation-fu. For example, when “here” is mispelled, I used “correct that” and “choose 1”.
“New line” gets me to the second line. “Select word” highlights the most recent and “Capitalize that” changes “revere” to “Revere”. The next line after that is just ridiculously hard. I’ll leave that one as an exercise for the reader. Finish it off with “semicolon. press Return key”.
The rest is easy, particularly because TextEdit did the uppercasing on my behalf. Don’t forget to insert a new line and say “period” (Or, I suppose, full stop. Hi Paul.) at the end of the sentence.
As with iOS, Catalina appears to be using a scaled down version of Dragon Dictation so it’s always helpful to be able to use the Dragon documentation, even when you run up against some pretty hard edge cases.
It’s honestly not the worst dictation system but I prefer the one on iOS.
Based on “full stop…”
Do you perhaps have English (UK) selected in date formatting or (apparently not) dictation language? I’ve found that text-to-speech with a British English voice reads “18 April” as “the eighteenth of April.” Maybe it goes the other way round as well.
Or you don’t and I’m extrapolating at random.
I just say “period”. However on both iOS and macOS, you can say “full stop” as well. (I discovered this when writing Talking to Siri with Steve Sande, where I did extensive testing on all the dictation features.)