If you want to discover what the human voice is capable of, listen to Humphrey Bower narrates the audiobook version of Shantaram by Gregory David Roberts.

In that , Mr. Bower emulates the voices of men AND women from India, Australia, Britain, America, and other locales. He renders distinct voices for at least 100 different characters.

You'll find a link to the audiobook and to my with Humphrey Bower in the comments.

So here's something to think about:

(Irish) As speakers, shouldn't we be able to portray a variety of characters, especially when we deliver ?

(older, southern) Yeah, as I've gotten older, I've come to believe that accents are a trick that any worth their salt should have in their bag. What do you think, Martha?
(Woman) I probably won't convince you that I'm really a woman, but if Dave is sharing a conversation with a lady, this voice is good enough to let the audience know who's doing the talking.
(pompous british) Alright now! That's enough of that!

Even if all you do is lower your to portray a bully or authority figure, or raise it to bring the audience back to your childhood days, the impact of voice changes on your audience is profound.

(valley girl) Plus, accents are like so fun to play with!