The sound is created by the vibrating of the deeper tissues far down your throat near your lungs. The goal is to create a deep vibrating sound with your deep throat. While doing this, close off the upper part of your throat like you are going to cough, or even do a slight cough to get the vibration started.
Then slowly take a deep breath and exhale it quickly, in about one second, which is about as fast as the air will go out. It helps to place your palms on the top of your knee caps to support yourself in this position. Stand up and place your feet wide apart, then lean forward to where your body is in as far over toward a horizontal position as you can easily do. When you get something in your lungs try this. This proposed technique is a more continuous shaking than a cough. It’s different than an ordinary cough which is a compressed bolus of air being rapidly expelled and creating a forceful wind which usually dislodges and expels the offending stuff. Basically this is a method for vibrating the windpipe to loosen bits of material stuck there. This technique is for clearing small pieces of material or liquids that have gone so deep into the windpipe or even into the lungs that they refuse to come out with an ordinary cough.
Rather, it’s for a slower type of also life threatening problem, that of having stuff down into your lungs and not coming out which can cause an infection, which might turn deadly. But, what I am proposing here isn’t for that type of instantly life threatening problem. It is very serious when people inhale a chunk of food which gets stuck in their windpipe and that requires another person to do the Heimlich maneuver to clear it out, or they die of suffocation. Most of the time people just cough when they have gotten something down their windpipe and it clears immediately. Inhaling food or liquids can be very annoying and dangerous and it’s a good idea to learn this coughing technique for when you just happen to have a serious problem.