Hi @craigljh.

Thanks for reaching out and bringing this up to our attention, let me help and try to figure this out.

When issues like this spring up,  the more information we can gather will help us resolve the problem. 

• Is this happening when watching a specific program?
• When it happens, kindly check on this link to see what might Google Assistant heard: myactivity.google.com
• If your Google Assistant-enabled device is very close to a Sonos speaker, try moving it further away and see if it will happen again.
• You may also try to ‘mute’ the microphone on the Beam and see if the issue will persist

If none of the above steps are helping resolve the issue you're having, you can try removing Google Assistant from Sonos and setting it up again. This will ensure that your Sonos is using the correct Google account and re-establish the connection with Google Assistant servers.

Let us know how it goes and if you have any questions feel free to reach out, we’re always here to help.

Assuming Google is the same as Alexa this is called 'ducking' and is deliberate so the device can hear the instruction.

No idea whether you can stop it because I don't use GA. Questionable whether it is a good idea to do so.

Edit sorry just reread and picked up the 'as if'. Is there someone else saying this to another Google device?