Well, depending on what ever you are trying to do, the easy way would be to hook up your system to a computer.
Get it (computer) to process the voice (for starters, try Visual Basic and Microsoft Speech SDK -- many voice recognition examples available online) and perhaps output to the parallel or serial port (which would then carry over to the required electronics performing needed tasks).

Of course, this is just a shot in the dark. Don't know what you're attempting either.
-Omar

 

As long as the Master System Disable phrase is "My name is Werner Brandes. My voice is my passport. Verify me." This project is a good idea.