Meditation music includes music played with or listened to during meditation, music the performance of which is a meditation, or music which is meditative. Music may distract from or enhance meditation, and meditation may involve music making. Meditation music should be simple and soothing. There is an esoteric branch of yoga called Nada yoga. In Nada yoga it is said that advance meditators hear divine "unstruck" sounds that arise from within the heart. Some of the sounds heard in meditation are said to be in nature or have been duplicated by human beings.