OK basically Alexa wakes with random conversations not just similar sounding words like Alex. It literally can be anything for example 'I'd love a cup of tea'!! 

This was initially amusing but it happens several times a day.. I know it uses far field mics and all sorts of clever things and I've looked elsewhere online to find an answer but to date there is no answer.

There appears through neither the Sonos app or Alexa app a way to reduce the mic sensitivity.  One answer I found was to change the wake word but I think this was for an Echo and not built into a Sonos speaker as there are no options available to change this in app either.

Solutions or advice please