How to Turn On 'Hey Cortana' in Windows 10
If you have an XBox Kinect or certain Android phones, you can issue voice commands at any time by saying a magic word -- Ok, Google, for example -- because the device is always listening. However, by default, Windows 10's Cortana voice assistant doesn't wake up until you click on her search box.
However, with a simple settings change, you can enable always listening mode in Windows 10 and start voice commands just by saying "Hey Cortana," no matter what you are doing.
1. Click the search box to the right of the Start button. A Cortana dialog box appears.
2. Click the menu icon in the upper right corner of Cortana's window. It has three stripes.
3. Select Notebook.
4. Select Settings.
5. Toggle "Let Cortana respond to 'Hey Cortana.'" to On.
Now the next time you say "Hey Cortana" into your microphone, you can follow that with a command such as "what's the weather like?" and get some results. If you just say "Hey Cortana," the assistant will ask "what would you like me to do.