Although Facebook has already said that they do not use their app to listen to the conversations of their users, many have found too many coincidences around the advertising that appears in the application.
Let's take an example: you stay with a friend and you start talking about blinds. After a while, you enter Facebook and coincidentally appear ads related to blinds; The most surprising thing of all is that you have not looked for anything in the network related to the topic (remember that advertising usually uses our habits when surfing the Internet).
The same happens with the big G, which shows its ads in large part on the internet and also seems to use the microphone to detect those keywords we say and based on this offer us the most timely advertising.