VoiceCommander

Voice Commander is an app that lets you speak commands to your Mac. The app can listen to you and carry out pre-defined commands when it hears and recognizes one of your commands.

To add a command, you simply have to give it a name and specify what you want the app to do when it hears it. Unfortunately, the options are limited. Voice Commander can only press keyboard keys or generate a mouse click. You can't tell it to open an application or launch a script, unless you figure out a way to do it via a keyboard shortcut.

When you add a command, the app will use your Mac's built-in speech system to say it out loud and when it detects something similar, it will carry out the command. My voice isn't anything like the Mac's default machine voice, so I struggled a bit to get this app to understand what I was saying, and when it did detect what I was saying, the command wasn't really executed. There is a feature called "echo commands". This makes the app speak the command name out loud when it recognizes it. This serves as feedback. Well, when I was testing it, the app did recognize the commands, because it repeated them for me, but the actions that I had set didn't seem to work.

I might just not have been using the app correctly, but I honestly tried with different commands and different key combinations.