Sounds like your TV (or cable box) is sending a signal to the Sonos, which is reproducing what it is asked to. Have you submitted a system diagnostic within 10 minutes of experiencing this problem, and called Sonos Support to discuss it? They would likely be able to tell from the data in the diagnostic. 

When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

If it sounds like an alarm, make sure you don’t have any Sonos or Alexa alarms set accidentally.