Re: "...some voice commands may be transmitted..
Let's be fair. Riker would need to provide a command override to the privacy settings. Once his envy became apparent, and his knowledge was found to be too great, Picard would check the system and BAM: "Ensign Riker reporting for duty"
Further of course, the vessels of Star Fleet will be command vessels, and authorized personnel will need the ability to - within very strict privacy and command override protocols - to access information if it is deemed necessary for the safety of the people aboard and the integrity of the mission.