The "default voices" are Windows text to speech voice engines, so how many you have is completely dependant on what version of Windows you're running.
I believe Windows 8, for example, has 2 female and 2 male voices as standard.
Arguably the best quality voices are the IVONA voices, but that quality comes at a premium of around 40 euro for the software. However, the "Amy" pack sounds almost identical to the voice in Elite, so there is a definite advantage to using it.
You do get 30 days free with the Ivona pack, so it might be worth trying at least.
To do it, just download and install the Ivona software from here:
http://www.ivona.com/ the website even gives you an example of what each voice sounds like.
Make sure you close and re-start Voice Attack after Ivona is installed, then create a new command (or edit an old one) and on the left-side buttons select "other" then select "say something with text to speach". Then set whatever Ivona voice you installed as the voice to use and type in whatever you want it to say. There's even a preview button, so you play around with words and punctuation to get it to sound right.
It's actually painfully simple.
You can take it even further by using variables to get interactions with the ship.
For example, I have mine set up so that when I exit supercruise I say:
"Ship, target the station"
The ship then replies "Confirmed" and opens the left panel, moves to the contacts tab, targets the station, closes the panel, then says "Would you like me to request docking clearance, Captain?"
I can now say "No thanks", to which the ship will reply "As you wish." and nothing further happens, or I can say "Ok" and the ship will then open the left panel again, access the station in contacts, and requests docking clearance. It then pauses long enough for docking to be granted, and it then sparks a random landing-based conversation.
So the ship might now say "Please check my fuel levels when we land." or "I hope this station doesn't smell as bad as the last". It might even say "Would you like to listen to some music while we land, Captain?" to which I can again reply "ok" and the ship will randomly play from a selection of tunes. Depending on the music played, the ship will even occasionally comment on the music track after it ends.
There's also a few back and forth jokes and insults. So occasionally the ship might say "I like this station. It reminds of when I was first built, when my cargo hold didn't smell of fish." If I then replied with something like "the hold doesn't smell of fish" the ship finishes by saying "oh? Then it must be you, Captain. I suggest you take a shower when you land".
You need a lot of randomness to ensure it doesn't get repetitive, but it's surprising how much having actual voice interaction with your ship improves the feel of it.
