I've used say.app off and on for many years to play around with the OSX say command, and grab the occasional text-as-audio file for various projects. It's the quickest and easiest way to get speech in digital audio form via a GUI on a Mac that I know of (awfully specific, but still useful!).
Unfortunately, say.app never got beyond beta status (still works fine) and hasn't been maintained since 2006(!). Furthermore, I've wanted a coding project to tinker with and Xcode was looking lonely, so I thought to myself "I should make a better say.app!".
Since there's no source code available, I just dug into the Speech Synthesis API and built (most of) it from scratch. I call it Utter because it's a synonym for "say", it's short, it's memorable, and it's kind of silly (and I couldn't find anyone else using it in my short Google search). There is some functionality from the original application I haven't sussed out yet, but the guts are there and functional. I even made a minor adjustment so that when you choose to save the audio to a file, it will still play through the speakers at the same time (say.app is silent when saving to a file). I plan to add additional functionality as I figure out how to harness the speech synthesis system better.
Furthermore, now there will be a modern, public repository for such an application that anyone can see and build upon. I'm still a pretty novice Objective-C programmer, so I'm sure my code can be improved, and putting it on Github seems to be the way you put yourself out there and get better nowadays.