The device acts like a stethoscope and listens directly from the sternum. When you use the device for the first time, you need to calibrate it with your voice and set the speech and breathing thresholds that you would like to record or be reminded. By filtering frequencies, we can detect speech rate, breathing and heartbeat. Does it make sense? Many thanks for your kind words: you do not always hear that your project is 'super cool' :)