Sneak Peek at Full Series

Yes, there's actually a signal that only Fi-leads have (or very Fi-heavy, Fi-secondaries) which is an airy-voice. It's a breathy and light/fairylike voice. This comes from having strong Fi emotionality seeping through at a constant rate. This usually only happens in non-jaded Fi users who don't coat their Fi with Te. So their voice actually does carry emotional expression. Jackson, 50-Cent are examples of this airy voice, as well as Evanna Lynch: youtube.com/watch?v=49HBeUK4hk8

So unlike Fe voice, which adds it's emotion in pushes and distinct points of emphasis, Fi voice remains at a mono-tone of constant whispery feeling. So both Fi and Te will be less drastic in their vocal variations but one will be accidentally radiating a consistent emotional aura, and the other will be consistently radiating a flat/dry aura and voice.

Mmm, tentatively yes, the loudness is indicative of Se>Fi. It's more of a fourth-hand effect though, from having more energy/momentum and excitation which adds more power to the articulation. FiSe's can be loud at certain times and SeFi's can be quiet at other times so it isn't a *hard* signal, but relatively more indicative of one than the other.

Not quite. The reason NeTi (and NeFi) are more predisposed to "introverted behavior" is because Ne is a process that can self-stimulate with very little tactile input. You give an Ne-lead a novel object, like a video game, that's more than enough of a staring-point from which they will extract dozens of other abstractions to entertain themselves with indefinitely.

So For Ne-leads, a single tactile stimulation goes a longer way. A single toy or object generates sufficient data to keep them busy for hours. So an Ne-lead can get lost in, say, reading a book --- their mind is engaged with the external world (the book) and generating ideas, associations, imagery at a very fast rate --- but outwardly it will appear as though they're introverting even though they're interacting strongly with the environment.

Such is not the case with Se-lead types. And this is because of Ni. The sensations they absorb are streamlined and stored through Ni as having a certain most probable implication, and the loop stops. So with every new stimuli, it is quicker to find an association within Ni and not need to continue dabbling with it like Ne does. Another stimulus is soon needed, as the desire to keep exploring persists and drives them into more tactile territory.

Lol.
I can't say much more about her from text alone..
That habit doesn't truly discern anything cognitively.

The exact threshold and what is stimulating varies between individuals. Not all Ne users are into videogames (was just an example), and not all Se users are into sports, etc. There's crossover. What *is* constant is what I said about Se storing the data quickly into Ni and moves on to a new stimuli, while Ne dabbles/plays with the data and manipulates into different forms before putting it down into Si. And even then it may pick it back up again several times, never completely done with it.