This along with much else that’s pointed out make the whole devices capturing audio to process keywords for ads all seem unlikely, but, one thing worth pointing out is that people do sell bad products that barely or even just plain old don’t do what they told their customers it would do. Someone could sell a listening to keywords to target ads solution to interested advertisers that just really sucks and is super shit at its job. From the device user’s standpoint it’d be a small comfort to know the device was listening to your conversations but also really sucked at it and often thought you were saying something totally different to what you said but I’d still be greatly dismayed that they were attempting, albeit poorly, to listen to my conversations.