Alexa is always listening but not continually recording. It doesn’t send anything to cloud servers until it hears you say the wake word (Alexa, Echo, or Computer). But listening for wake words is harder than you might think.
Fine-Tuned Microphones Pinpoint Your Voice
Voice assistant speakers, like Echo and Echo Dot, typically have multiple built-in microphones. The Echo Dot, for instance, has seven. That array gives the devices several abilities, from hearing commands spoken far away, to separating background noise from voices.
The latter is especially helpful for wake word detection. Using its multiple microphones, the Echo can pinpoint your location relative to where it’s sitting and listen in that direction while ignoring the rest of the room.
You see this in action whenever you use the wake word. Stand to the side of an Echo or Echo Dot and say the wake word. Notice the ring lights up in dark blue, and then a lighter blue as it circles and “points” toward you. Now, move several steps to the side and say the wake word once again. Notice the light-blue lights follow you.
Knowing where you are, helps the device focus on you better and tune out noises coming from elsewhere.
Short Memory Keeps the Speaker from Holding Too Much
It records continuously but wipes everything it just recorded at the same time. That short attention span means all it can hear is the word, “Alexa,” and not much more. Three seconds, though, is long enough for that word to be recorded, examined, and acted upon appropriately.
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