>newer Alexa devices have "presence detection"

Not even the biggest privacy issue of using Alexa devices. I think listening you 24/7 is a bigger potential issue.

Not sure if Alexa has this, but cheap mm-wave wideband multi-GHz sensors(or radars more accurately) now enable more finely grained human presence detection and also human fall detection[1] with the right algos, so you can for example detect if grandma in the nursing home fell down and didn't get back up, but in a privacy focused way that doesn't resort to microphones or cameras. Neat.

>Reminds me of the story about how the Google Nest smoke detector had a microphone in it.

Vapes have microphone arrays in them to detect when you're sucking and light up the heating element. Cheap electronics have enabled a new world of crazy.

[1] https://www.seeedstudio.com/MR60FDA2-60GHz-mmWave-Sensor-Fal...

The Nest smoke detector microphone was never really secret. It was part of the monthly self test to determine if the alarm was working. It would send you a notification telling you it was going to sound the alarm and that it would be listening for the sound to confirm it was working.

It was listed in the features for the 2nd gen units. https://support.google.com/googlenest/answer/9229922#zippy=%...

Edit: That article isn't about the Nest Protect (smoke detector), it's about the Nest Secure, an alarm system.

How many people have Alexa devices vs wifi? I got gifted an Amazon Echo Dot some years ago. We set it up and switched it off later the same day because it felt creepy to have the thing listening to everything we said.

Every capacitor can be a potential microphone ...

That reminds me of the other story where the Pixel phones come with a microphone that turns on every time you make a call!

The phone actually records audio and sends it remotely to someone else.