I'm kinda lucky, my voice is so distinctive that it's easily recognized, no matter what I say.
Blame it on Cousin Jeff (NASCAR announcer) or Cousin Earl (Thundercats-Panthro)

Dang near the whole family is like that, golden voices...might have something to do with having so many preachers in the family...trained voices start with a good basic speaking voice. Genetics help...
On the other hand, not everone has such a distinctive tone & timbre...so you have to use rotating passwords.
Nobody in their right mind uses the same words for every op.
KNOWING the people in your squad makes more than a little difference. The way someone walks, talks, and tends to act can help one determine a lot more than who is coming, it can also tell you their state of mind.
This whole discussion reminds me of those little Kriket Clickers from WW2, they would click once or twice, the other person would click either twice or once.
That got screwed up by Germans who worked the bolt of their K98, making clicks...LOL
Plus, when one uses their voice to call out, it alerts people and things farther away than sight...
Imagine you are creeping around someplace and about 50-10 yards away you hear "Texas!"..."Star!"
You know that someone else is in your field of play...
Throat mikes are the way to go...with lithium rechargeables. Add a solar recharging pad, and you are set for a decade of OPs.