Locate the Speech Synthesis Settings control that you have just added to the project. Here, you can change the parameters of the voice. Change a parameter, and make the robot speak again - notice the difference?
*Note: Not all parameters are used with some voices. For example, the default voice that is installed with Microsoft Windows does not accept all parameters. This means you may change a parameter, such as Gender, and the robot voice did not change. This is because that particular selected voice does not have an option for that parameter.
Play around with the parameters and make your robot talk or tell jokes!