Sound is an important tool in our robotic toolkit but you will want to do more than just play music. Let's make our robot speak. You're going to start by enabling eSpeak, an open source application that provides us with a computerized voice. It is a voice generation application. To get this free functionality, download the eSpeak library by typing sudo apt-get install espeak at the prompt. The download may take a while but the prompt will reappear when it is complete. Now, let's see if the Raspberry Pi Zero has a voice. Type the espeak hello command. The speaker should emit "hello" in a computer-generated voice. If it does not, check the speakers and the volume level.

Now that we have a computer-generated voice, you may want to customize it. eSpeak offers a complete set of customization features, including a large number of languages, voices, and other options. To access these, you can type in the options at the command-line...