I usually set it at around the middle 50%
The safest way to not damage your ears and have the volume loud enough for effective listening is to play the masked version first at a comfortable volume and then switch to Ultrasonic at that same volume or a tad lower.
Here’s what you need to know about ultrasonic programs: even though you can’t hear them, they’re actually very, very LOUD. Regardless, they’re generally safe if you listen to them at a reasonable volume level. While listening on speakers, use Frequensee to determine the decibel level (db, left side). Make sure to never play an ultrasonic program over -20 db.
You find all you need to know here:
I played it and and my medium is abit above 50db
way too much. -20db is the maximum.
Sorry i meant it was abit above -50db
here is another thread about ultrasonic volume
hope that helps