Perhaps it’s this…

Is the One-SL grouped with your Sonos Beam and does the Beam have the Alexa voice assistant installed, or are you using the Alexa assistant via the Sonos Skill? If so, then it’s quite likely that you maybe listening to an Alexa Alarm, which you can cancel by going to the ‘Alarm & Timers’ settings in your Amazon Alexa App.

Thanks for your reply. Not quite sure why but it has stopped. Couldn’t find any alarms or timer set on anything. But it’s all good now thanks