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| Joined: | Sep 22nd, 2008 |
| Location: | Doylestown, Pennsylvania USA |
| Posts: | 130 |
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Experimenters looking for earth sounds have built receivers that respond to base band or audible frequencies that are generated from the earth and can be detected on magnetic fields. They have sensitivity similar to radio frequency receivers but are designed to amplify audio frequencies and filter out power line interference at 60 Hz.
The typical sounds heard are buzzes, clicks, whistles, but angelic choirs, and voices are also heard.The block diagram for these would be similar to a magnetic coil connected to a device like an audio recorder with sufficient gain to record and play back the earth sounds.
Joe