Svaram Planetary Tuned Sound BridgesThis listing includes one sound bridge of your choice and a mallet. Earth Rotation 388. 36 Hz The Svaram Sound Bridges span their vibrations into the mid range of the planetary frequencies. Played with a gentle hit from the side of the swing suspended under the supporting arches, they create a subtle doppler effect, spreading their precisely tuned vibrations into your environment, inviting a more relaxed perception of the specific planetary qualities.