We know of several drugs that cause such voices, so if you force that on yourself here on Earth and go to Mars afterwords, the question is: would you still hear those same voices? Until there is more solid evidence for that, it is easy to doubt previous Earth only research.
Once we get to Mars, I think this subject will no longer be so taboo. I think the physical differences are so significant that it won't be classified as hallucinations, anymore. We know they aren't only hallucinations, as we studied crystal radios and didn't ignore the obvious. I finally got one reasonable answer why such research was stopped here on Earth. I posted research about snails given "drugs" once, but law forbids the published details over how such specimens handled their heighten intelligence. Of course, anybody with few years of experience in their garden surely does not want more intelligent creatures to eat up their crops.
We have seen science fiction movies, like Dune (1984), where giant sand worms brisked their way through the sand terrorize with their appetite for the source of any sound made. The sound in the movie was by people who walked across the sand dunes unlike any other hallucination heard and classified. It is obvious people have gone way out of their way in such expressions in how they avoid their can of worms from knowledge they heard through the news. What is not science fiction is the real threat that these snails and worms have really become intelligent under such experiments.
We have done pretty good in the way we have kept most creatures dumb. At the same time, however, we have kept ourselves dumb, as we have met legal barriers every time we supposedly found new knowledge. What we really found is that more and more people identified the same knowledge and were met with the same events of hush-hush. Literally, anything related gets put "on hold." I don't blame such actions, as I acknowledge that we need our food. Mars challenges that thinking and those barriers, nevertheless, with greater weight of curiosity and physical distance.