Sine waves are used to create beats and interference in this ambient noise recording by yantra. 23 tones in all are used, including 18 solfeggio frequencies arranged spatially in a hexagonal pattern. from the album ‘hridayam’. free download! this is also spectacular for meditation. ‘om’ is noisier and preparatory and ‘aum’ is cleansing and relaxing. these works lend a sense of grounding and expansion, as they are tuned to the earth’s harmonic frequency.