>>48789
A lot of files that contain background voices are badly mastered so that you can only hear them when the main voice is already way to loud.
Even though your brain won't process anything, you cannot hear, when consciously focusing on it, you don't want to listen at such a high level for any longer than necessary. Other than maybe doing so to quickly check what is being said, it is better to ignore the background sounds at all, if the files are not mastered correctly.
Also since most files tend to be somewhat long and our ears get exhausted and eventually destroyed just as our muscles (but without the healing part), it is best to use the lowest comfortable volume level possible.
This doesn't mean you should have a hard time understanding the hypnotist, but as your brain has to focus on the instructions anyway and you ideally are in a quiet environment there is no need for unnecessary loudness.
Additionally a good tist won't need the perceived increase in authority a louder listening level may convey.
The only problem with low listening levels is the way our ears attenuate very high and very low frequencies, so the recording or binaurals might sound thin, if the creator has mastered it at a higher level. You can however compensate for this by slightly increasing the bass and treble sliders on your playback device or using a bass heavy headphone, that will generally reach a pleasing sound signature at a lower threshold and likewise it will sound boomy sooner. Therefore an equalizer, or even better a loudness compensation method, is the tool of choice.