Update: I might have found a solution to the blocking. I noticed that my body automatically clenches my throat when I hold my breath. My theory is that the un-clenching for speaking doesn't happen fast enough so the first sound hits the blocked of throat and causes a panic. I have maybe found a solution how to stop the clenching, but I don't know if it's placebo or a real solution. I keep a puffed up chest when breathing. So I inhale into my chest, keep the breath in the chest area and then just continue to breath with intercostal/belly. Maintaining an expanded chest prevents the clenching of the throat. Imagine there is a long solid plastic tube that leads from your mouth into your lungs. This plastic tube has an empty core without any obstruction, just air. Try this first when lying down on your back. But like I said, it might be a placebo, so don't stake your hopes on my lil experience