Beltone "Invisible" Eyeglass Hearing Aid The Beltone "Invisible" eyeglass hearing aid was made by Beltone Electronics Corporation of Chicago, IL in 1957. The electronics required the use of both temple pieces. This hearing aid was a bone conduction hearing aid, thus it didn't require an ear mold—hence the name "Invisible". The Beltone "Invisible" was a 3-transistor aid. |  | Click picture for larger view | | |   | | | |
| View of the bottom of the left temple piece of the Beltone "Invisible" showing the volume control/on-off switch (midway along the bottom of the temple piece). The serial number is visible in the top left corner. |  | Click picture for larger view | | | |
| View of the behind-the-ear portion of the left temple piece of the Beltone "Invisible" showing the microphone port (large black hole near the tip). |  | Click picture for larger view | | | |
| Inside view of the right temple piece of the Beltone "Invisible". The bone conductor transducer was held snuggly against the inside of the case by the two brass screws (upper right). Notice the wire (lower left) showing how one conductor came around the corner from the eyeglass frame and connected to the temple piece via a screw. The other conductor was soldered to the metal hinge. |  | Click picture for larger view | | | |
| View of the inside of the left temple piece of the Beltone "Invisible" showing the metal battery door. This hearing aid used a No. 630 battery.
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| Rear view of the eyeglass part of the Beltone "Invisible" showing the wires (across the top of the frames) connecting the electronics in the two temple pieces to each other. |  | Click picture for larger view | | | |
| The Beltone "Invisible" had rather ornate temple pieces. |  | Click picture for larger view | | | |
| The Beltone "Invisible" showing the two temple pieces in the open position. |  | Click picture for larger view | | | |
| The Beltone "Invisible" in its original case. |  | Click picture for larger view | | | |
| Outside view of the case of the Beltone "Invisible".
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