How to Enable Siri on your Mac
When first installing Sierra, you’re given the option to enable Siri. If you decided to decline Apple’s kind offer, you’ll need to visit System Preferences to activate the service.
Click on the Siri icon in System Preferences and you’ll be presented with several options.
You can choose your language, the voice Siri will use and whether to offer audio feedback.
If you’re likely to be using Siri in public places without using headphones it’s advisable to turn this option off.
Then choose a keyboard shortcut used to wake Siri up. You can select from predefined options or opt for Customise.. to create your own.
Finally, you can check the box to Show Siri in menu bar. A small icon will appear at the top right of your screen, clicking on it will activate Siri as an alternative to using a keyboard shortcut.