Make sure that there is no surveillance in the room before the discussion and that it is no longer limited to spy movies. The great success of connected property gives everyone the opportunity to worry about overhearing private conversations. A Bloomberg investigation raised legitimate concerns and found that spokespersons using the Amazon Alexa virtual assistant were accidentally heard by company employees.
Today, there are mobile phone jammers that work on the same principle, but are only effective for mobile phone bands, because ultrasound tends to move in one direction. The speakers on the wristband are subject to the same limitation: for this reason, researchers placed them around so that they could transmit radio waves 360 degrees. For the same reason, they designed a cell phone jammer that can be worn on the wrist. Because we often speak with our hands, the ultrasound will spread more, maximizing its effectiveness.
This would not happen if they were equipped with cell phone signal jamming devices designed by researchers at the University of Chicago. It is obscured by ultrasonic speakers, projecting a sound wave field around the wearer, which people cannot hear but destroys nearby microphones. It is reported that Amazon employees did not record the conversation but heard white noise.