It appears that Microsoft decided that its voice-controlled assistant can no longer be disabled in Windows 10 after the upcoming Anniversary Update. So they can now be listening in on everything someone says in a household. Is this immoral? Microsoft probably doesn’t think so. But then you discover that Microsoft also decided that school children will not be spied on (so that would be immoral?)
A hardware killswitch is probably the only way you can make sure Cortana doesn’t hear you, but some manufacturers don’t supply those anymore.
Microsoft is not alone in wanting to listen in on your bedroom performance, Google also sneakily placed a recording system on all computers running an up-to-date version of Chrome. They even managed to infiltrate the free software base of Chrome, Chromium. So do Chrome users on Windows 10 now have two spies in their home? Seems that way.