You have this device built in to you body already. In yoga there is a practice called Ujjayi Breathing where you restrict airflow in and out of the lungs via t

You have this device built in to you body already. In yoga there is a practice called Ujjayi Breathing where you restrict airflow in and out of the lungs via the the throat, making a soft sound. This is often combined with meditation or sometimes uses in very energetic situations to calm the breath.