A very interesting article. One can "see" without consciously realising it - person without the visual lobes was able to navigate through the path with obstacles.
Supposing that when LSD allows to see the sounds, it's the visual cortex that is temporarily mis-wired.
hmm... Though, here they they say that the brainscans with LSD did not reveal the increased activity in the visual cortex... I wonder if there's any scientific literature on the topic.
Anyway, a step further - one consciously analyses the information seen. Could one "see" by creating within themselves the illusion that they see, at a higher level of abstraction, as soon as they genuinely believe in it ? And how to make that in a predictable manner ?