For free-form meditation to music (just listening), albums like this are great:
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If you want to strengthen your concentration through music, it seems more useful to have a very clear bass or drum line.
If you just want to meditate without any specific goal - just to improve, or to relax, or whatever - then progressive song arrangements work really well.
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Your mind has an easier time breaking experience down into stereotyped patterns if it can access predictable rhythms.
If you want to stay on task, or fall into a trance, you can listen to the same boring song on a loop for hours. It works.
But only if that's what you're after.
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It's really key that it's boring.
Something engaging will absolutely take you out of what you're doing. This is why most non-specialized mantras are fairly straightforward and easy to follow.