Some train themselves to hear the Saut-e-Sarmad in the solitude, on the sea shore, on the river bank and in the hills and dales; others attain it while sitting in the caves of the mountains, or when wandering constantly through forests and deserts, keeping themselves in the wilderness apart from the haunts of men. Yogis and ascetics blow sing - a horn, or shanka - a shell, which awakens in them this inner tone. Dervishes play nai or alghoza - a double flute - for the same purpose. The bells and gongs in the churches and temples are meant to suggest to the thinker the same sacred sound, and thus lead him towards the inner life.