There is a lot of propaganda and fear-mongering on the internet from sources whose reliability or efficacy in esoteric matters cannot be vouched for.
There is no danger to becoming aware of one's internal states, constitution, or psychic nature, since this sound naturally irradiates from the brain. Just as it is not dangerous to become aware of one's breathing, likewise there is no harm or fault in becoming aware of the Anahata sound, the natural product of one's vital body and active psychic forces within our subconscious nature, which we urgently need to realize within ourselves here and now.
Joyful in hope, suffering in tribulation, be thou constant in thy prayer.
Benedictis, qui venit in nomine Domini. Osanna in excelsis.
"Blessed is he who comes in the name of the Lord. Hosanna in the highest!"