I wonder how many kinds of "meditation" there are? Adzel is in a trance and Chee Lan has to make a considerable racket to gain his attention. (David Falkayn: Star Trader, 363.) Would he be in danger of burning to death if a fire alarm sounded? In zazen, "just sitting" meditation, we remain fully alert with eyes open facing a wall. We sit in a quiet room but hear any background noise and are able to respond if necessary.
It would be good to experience every kind of meditation in order to find out which is most helpful. I knew a guy who agonized between zazen and Tibetan visualization before opting for the latter. That was obviously right for him.