At first I was going to disagree, but then I decided the statement is correct. For me to be in a state where I experience an OBE, I am not in wakeful consciousness. It is a semi-sleep state of sleep paralysis. Even when I open my eyes the rest of my body will not move. I don’t call this a state of ‘sound body.’ And in this state, the mind is subject to all sorts of fantasy. The OBE experience itself is a mental construct, a fantasy occurring due to a specific brain state. So, it too, is not ‘sound.’
Again, I have said, anyone can learn to do this. It is easy. It takes about a month of consistent practice.