Hi I'm back armed with more questions 
Elyse you mentioned that 'High and low modality are very important in speeches'. Is modality also important in other modes of text? Are there particular modes of text that modality is usually present? Would the effect of high/low modality in these texts have the same effect on the audience? I was also wondering would it be correct to say that the general effect of high modality incites a lot of emotion and power. It motivates the audience to feel encouraged to act in that way.Would there be other effects of high modality on the audience?
I was also wondering what would be the best way to word the effect of low modality? low modality passively incites action from the audience?Would there be other effects of high modality on the audience?
Modality is definitely important in other modes of text - but it is most prevalent in speech/dialogue. So in short stories, novels, or even poems, modality is used as well. About the general effect of high modality - you're absolutely correct! There could be other effects of high modality...it could make someone feel depressed rather than encouraged. I mean, a bully could use high modality to gain power, but they wouldn't be leaving their victim feeling encouraged. That sounds like great wording about low modality!
I was also wondering you talked about 'Basically, high and low modality have so many different purposes, and both can be inviting and persuasive. You need to identify the intended audience of the work, the content that the person speaks about, and their intention with delivering the content. Those three things should be a good indication of why and how modality is at play'. I was a bit confused about the two later points ', the content that the person speaks about, and their intention with delivering the content'. Is it basically the content of a text and the purpose of the text? I'm not exactly sure how to why and modality is at play using these two points.
Yep, good question. So this is what I mean by the bully example above. If we have a bully delivering a nasty speech on why the wimpy kid is worthless - the audience, being the wimpy kid, and the content, being nasty words, has a depressing effect on the victim. But, if Martin Luther King's audience is oppressed people looking for answers, and his words are about how to find those answers, then the effect of high modality is that the audience will be empowered.
I was also wondering, if it is not too much of hassle,if you could explain how these aspects can construct voice please. I am also not sure what effect each aspect has on the audience.
•Adverbs used to describe the actual delivering of the voice in dialogue
"Never speak like that," she
whispered."Never speak like that," she
hissed.Here's the verb, in italics. See the difference it makes? Similarly, it works with the adverb.
"Never speak like that," she said
sympathetically."Never speak like that," she said
angrily.The adverb makes a lot of difference.
•Sentence type and variation (short, correctly formed? Long, jumbled?)
Someone's sentences as being long, jumbled, and confused...could indicate someone being very flustered. Someone using short, correctly formed sentences is in control, calm, and calculated, most likely.
•First, second, third person narration?
- First person: personal -> engages
- Second Person:
-Third Person: omitted -> broader view
Second person is rarely used - it's usually just quite recounting and matter of fact.
•If in third person, the omniscient narration?
The omniscient narrator is the third person narration that has the gift of knowing the thoughts and feelings of all of the characters. So they can say, "Mandy felt sad." They have an extra insight, whilst remaining third person. Third person limited narrator, is the other type of third person, where you are limited to just observing as a person would, without the insight of thoughts.
•Tone (which you already have)
Tone is hard to define - it's basically the overall ambience a person gives, the vibe they give off. A rude tone, an optimistic tone, etc.
•Stylistic decisions (embellished language, simple language)
If the language is plain and simple, that might be a reflection of their character. If they are embellishing everything, they are exaggerating and maybe too excited.
•Colloquialisms
Usually shows comfort with the person they are speaking with, or can be used as a way "in" to someone - showing that you're friendly and casual.
•Informal or formal register
Is the person speaking informally with colloquialisms like they're talking to Joe at the pub, or are they speaking formally like they are talking to the President.
•Do they use nicknames for some people and full names for other people?
Nicknames are usually used for people your friendly with. You don't call your Principal by his or her first name right?
•Diction
This comes with the delivery of the sentences - what are they emphasising? Is the refrain repeated with a deeper voice each time? Are the last words yelled to call to action? It's about the delivery

I apologize for bombarding the forum with so many questions 
I am trying to create a table that summarizes a technique used and its effect on the audience. That is why I am exploring and listing possible effects of a each technique on the audience.
That sounds like a super good resource to make! When it's all done, I'd love to see it!

Hopefully this helps!