Last night at midnight Alexa scared me silly. I had the volume up from playing music earlier, and she shouts out "I'm sorry, I don't know how to do that" without being prompted. Why is this? The only way to stop it is to turn it off, what is the point of having it?
When Echo's Mics are on it is possible that some other spoken word or sound matches the wake work "Alexa". I have had a few occurrences of "Alex" and "Alexander" waking Echo.
The only way to stop it is to turn it off
You may try turning off its Mic, when you do not wish Alexa to listen. but, functions such as Alarm will still work.