In the app’s settings, you can turn on an option that also makes the Echo beep every time it hears its name, and again after it’s finished transmitting—even more cues to help you understand when the Echo is transmitting audio.
You can also turn off the Echo’s microphones entirely when you need super-duper privacy; just press the microphone on/off button on the top.
OK Google and Google Home
Siri
As with Alexa, no recordings are made or transmitted until you say “Hey Siri” or trigger her using a key or a button on an Apple iOS device. Even then, Apple says it doesn’t associate the command with you; it assigns you a random number that’s associated with your request.
After six months, even that number is deleted. Apple keeps the actual, anonymized recording around for up to two years for testing.
If you turn off Siri at any point, all of your identifies and recordings are permanently deleted.
Cortana
Microsoft’s Cortana voice assistant gives you by far the most control. For example, she can perform many tasks even when you haven’t logged in with your Microsoft account: getting answers from the Web, translating phrases, performing calculations, setting alarms and so on. These queries have no association to you.
If Cortana needs access to any of your personal information, she asks first. At any time, you can open her settings and turn off whichever info-bits you’ve shared with her (for example: your location, your calendar and e-mail info, your sports team or restaurant preferences).
Microsoft doesn’t say how long it stores your recordings on its servers, but once again, you can delete them at any time.
