Amazon's Alexa assistant supports multiple 'wake words,' which serve as activation phrases for Alexa to start listening. Until now, this included "Alexa," "Amazon," and "Echo." Now Amazon has silently added "Computer" as a wake word, something that is sure to please Star Trek fans everywhere.
You can change the wake word on the online settings panel. This should work for all your Alexa-powered devices, be it an Echo or a refrigerator. Unfortunately, Alexa cannot (yet) raise shields or engage the warp engine.
Hopefully Google adds "Computer" as a hotword to Assistant in the near future, but as an optional feature. I know I say that word a lot, and my Google Home is already sensitive to "OK Google" commands in videos and commercials.