Listening to the voice in my MacBook Pro

I have no idea what key I hit, but suddenly, [Alex’s voice](http://developer.apple.com/releasenotes/Carbon/RN-Speech/index.html) is everywhere.
When I open a new Firefox tab. When I close one.
When a popup message appears. When I open System Preferences (to see if I can uncheck anything so the voice will stop talking to me!).
It was amusing initially but it’s starting to get a little obsessive-compulsive as it reads out every little step I take.
Admittedly, Alex’s voice is the most accurate and human like. I prefer listening to him over Bruce and Fred. There are [lots of things](http://www.widgetworld.nl/apple/leopard-tricks/3767-alex-speech-tricks.html) you can make Alex do for you.
But could someone please tell me how to turn him off? 🙂
[Update: Turns out I hit Command + F5 by accident and that turned Alex on. I’ve just put him back to rest.]