The intelligent speakers of our voice assistants and other devices with a microphone should not listen all the time. We know that unfortunately this is not the case, but there may be a solution if you are unwilling to be eavesdropped 24 hours a day.
Researchers at the University of Chicago have built an experimental spy bracelet. The device silences all mocrogons using ultrasonic transmissions from 24 mini speakers.
It does not matter where they are positioned or what they are heading for: the anti-spy bracelet blocks them all.
How the anti-spy bracelet works
The gadget exploits the non-linearities of its built-in amplifier to "scatter" the ultrasonic noise in the audible range and thus make all recordings useless.
The design of the anti-spy bracelet is not exactly trendy, nor does it have a technological appeal. Oh well, I say it: it's really horrendous, my mother.

But it works. Not only does it guarantee omnidirectional noise, but it eliminates blind spots (where transducers cancel each other out) through wrist movement. As a result, it is more effective than dedicated fixed jammers and can even confuse hidden bugs and microphones.
The materials and the interior fittings are not who knows what, this makes me think that the secret of this device lies in its form factor.
Developers they declare to the New York Times to have several proposals for marketing the technology. The sum, paltry, would be around 20 euros. A sort of holy grail for anyone who cares about their privacy and doesn't want to be intercepted by voice assistants or spies.
Any worries?
You know that I always play the devil's advocate when I see ethical doubts. We do not hide it: for many people who legitimately would like to safeguard their privacy, there are tides of criminals (and some politicians) who would get married with a similar device. How do we deal with wiretapping?