Better Results: Masked Subs OR UltraSonic Subs?

[Whisperer]

Then I would suggest combining your favorite meditation music with the ultrasonic track. If you use a computer, it's easy enough, just use 2 players, I do that all the time. Since you indicated headphone usage, 2 physical players wouldn't do the trick. If you use a portable player, you'd need to merge them very carefully into a single track or use special apps.