1. Crickets.
    I don't know why, but it triggers some deep sense of peace, like all is right with the world.
  2. The sound of the ocean receding over a pebble beach.
    Again, like with the crickets - it doesn't strike one as an obviously pleasant sound but it is so deeply, hypnotically, rhythmically soothing.
  3. Tibetan chanting.
    Specifically Tibetan chanting has a guttural quality to it (you know how Indian chanting is almost more nasal? - totally different effect), that, again, taps in to a "all is fundamentally well in the world" feeling.
  4. Bamboo shoots creaking and its leaves rustling in the wind.
    Especially when you are standing in the middle of a bamboo forest, the effect is otherworldly yet deeply cocooning.