How to make the most out of speech synth modifiers?

I’ve been hoarding for articles on how to edit the “say” command to make the voice sound more natural and the content more understandable, but I find that some of the claimed modifiers don’t do anything at all. Why?

I added “using Daniel” to this demonstration script because that’s my system voice. It’s relatively clear and not at all creepy and breathy.

Recap:

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# Original:
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say "On July tenth, you have a meeting in Paris." using "Daniel"

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# Sounds exactly the same:
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say "On 'July' tenth, you have a meeting in Paris." using "Daniel"

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# Sounds exactly the same:
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say "On [[emph +]] July [[emph -]] tenth, you have a meeting in Paris." using "Daniel"

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# Sounds exactly the same:
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say "On [[emph +; rate 165]] July [[emph -]] tenth, you have a meeting in Paris." using "Daniel"

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#The word 'on' will dip unnaturally low in pitch and perceived volume, then have a short pause before the next word; The mod works but isn't terribly helpful:
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say "On [[slnc 60]] July tenth, you have a meeting in Paris." using "Daniel"

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# The speed does change after each rate mod:
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say "On [[rate 400]] July tenth, you have a meeting [[rate 40]] in Paris." using "Daniel"

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# Some words that get pronounced hastily because they can't be emphasized using mods, may benefit from an invented alternative spelling, but while it may clarify the pronunciation, it can still introduce a new unnatural tone of voice:
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say "Everything takes hours to do. Everything takes owerzz to do." using "Daniel"

Hi. You can provide a significant emphasis given parenthesized text, however, making it more understandable is pretty subjective.

say "On [[emph +; rate 165]] July [[emph -]] tenth, you have a meeting in Paris." using "Daniel"

vs.

say "On [[emph +; rate 165]] (July) [[emph -]] tenth, you have a meeting in Paris." using "Daniel"

Oh I see, I hadn’t seen that before. I think that probably does what I had seen as the ‘July’ tip. I wonder why those characters would be interchangeable (and incorrect in the documentation that I’ve seen).

In your example, the emphasis mods are still ineffective, so the following stripped version is sufficient to do the trick:

say "On (July) tenth, you have a meeting in Paris." using "Daniel"

I agree, it’s a method to give emphasis, one that I didn’t know of, but in that example it’s counterproductive in terms of making the sentence more understandable. It’s much faster to type and keep track of than wrapping words into double brackets in the beginning and end, though.
Parenthesis work well in applications such as this:

say "Talking about comprehension (which) (by the way) was the first word I ever learned." using "Daniel"

But using commas will yield exactly the same pronunciation: :confused:

say "Talking about comprehension, which, by the way, was the first word I ever learned." using "Daniel"