siri not working on imac

If Siri doesn't hear or understand you:

• Make sure that you're using macOS Sierra or later. 
• Choose Apple menu  > System Preferences, then check your microphone selection in Sound preferences or Siri preferences. Or test with a different mic, such as the mic in your AirPods or Apple Earphones. If you're using a Mac mini or Mac Pro, you must connect a mic for Siri to hear you.
• If Siri seems to hear you but not understand you, make sure that your language and dialect are selected in Siri preferences.
• If Siri can't connect to the network or asks you to try again in a little while, check your Internet connection. 

Siri requires an active Internet connection. 