Make Sure You Enable This Amazon Echo Setting ASAP. Echo and Echo Dot are becoming more common in smart homes; but, how do you know Alexa is listening to you? Both to know when you can speak a command, and to know when a word or noise triggers the device to listen, it is handy to have an audible tone as well as the blue light at the top of the device. That way, you don't have to be looking at the device to know it can hear and record your voice. Go into Settings on the app, and set it to play a tone when it hears the wake up word. Be careful what you say after the tone. It is being recorded online.