Sonotone Model 700 Vacuum Tube Hearing Aid The Sonotone Model 700 vacuum tube hearing aid was manufactured by Sonotone International, Inc. of Elmsford, New York in 1946. The Sonotone Model 700 used three vacuum tubes. It was a two-piece unit (the batteries were external). It weighed 7.0 oz. (198 g) without the batteries and measured 3 15/16" high x 2 11/16" wide by 15/16" thick (10.0 x 6.8 x 2.4 cm). |  | Click picture for larger view | | |   | | | |
| Front view of the Sonotone Model 700 vacuum tube hearing aid showing the microphone grill (center) and the battery plug cover (bottom).
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| Left side view of the Sonotone Model 700 vacuum tube hearing aid. |  | Click picture for larger view | | | |
| Top view of the Sonotone Model 700 vacuum tube hearing aid showing the volume control wheel (left), the receiver cord plugged in (center) and the 3-position on-off switch (right). The 3-position on-off switch was something that Sonotone used. There was the "full on" position (2nd click) and the "bi-focal" position (1st click). In this position it "dimmed out" background sounds for clearer hearing in crowded, noisy places". |  | Click picture for larger view | | | |
| Top view of the Sonotone Model 700 vacuum tube hearing aid showing the receiver cord unplugged. Note the unusually long pins on the receiver cord plug. |  | Click picture for larger view | | | |
| The battery cables had a unique way of plugging into the Sonotone Model 700 vacuum tube hearing aid. First you pulled down the bottom cover. It just snaps off with a bit of a tug. |  | Click picture for larger view | | | |
| Bottom view of the Sonotone Model 700 vacuum tube hearing aid with the bottom cover removed showing the unusual battery cable plug arrangement. |  | Click picture for larger view | | | |
| Rather than just pulling the plug apart, your had to twist the plug 90° counterclockwise as shown. Then you could pull the plug off the center locking pin. |  | Click picture for larger view | | | |
| Close-up view of the bottom of the Sonotone Model 700 vacuum tube hearing aid showing the battery cable plug removed from the center locking pin. |  | Click picture for larger view | | | |
| Rear view of the back of the Sonotone Model 700 vacuum tube hearing aid showing the spring-loaded pocket clip. |  | Click picture for larger view | | | |
| Close-up view of the center back of the Sonotone Model 700 vacuum tube hearing aid showing the name (Sonotone), model number (700) and serial number (884400). To the left is the high-cut (A-B) filter shown in the "A" position. |  | Click picture for larger view | | | |
| Close-up view of the upper rear of the Sonotone Model 700 vacuum tube hearing aid showing the three-position (1 2 3) power control immediately to the right of the pocket clip. It is set to the "2" position. |  | Click picture for larger view | | | |
| Close-up view of the unplugged 2-pronged "A" battery plug (bottom) of the Sonotone Model 700 vacuum tube hearing aid and the top of a 1½ volt Sonotone No. 800X "A" battery. |  | Click picture for larger view | | | |
| Close-up view of the 2-pronged "A" battery plug of the Sonotone Model 700 vacuum tube hearing aid plugged into the top of the "A" battery. |  | Click picture for larger view | | | |
| Close-up view of the unplugged 3-pronged "B" battery plug (bottom right) of the Sonotone Model 700 vacuum tube hearing aid and the top of a 45 volt Burgess No. XX30E "B" battery. |  | Click picture for larger view | | | |
| Close-up view of the 3-pronged "B" battery plug of the Sonotone Model 700 vacuum tube hearing aid plugged into the top of the "B" battery. |  | Click picture for larger view | | | |
| Back view of the receiver of the Sonotone Model 700 vacuum tube hearing aid. Note the Sonotone "S" on the receiver cord plug.
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| Back view of the Sonotone Model 700 vacuum tube hearing aid receiver showing the receiver cord unplugged from the receiver. |  | Click picture for larger view | | | |
Side view of the Sonotone Model 700 vacuum tube hearing aid receiver snapped to the hard clear plastic ear mold.
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| View showing how the ear mold snapped to the receiver. Here shown unsnapped. This ear mold was made from an impression of the ear. See the original impression and this ear mold compared side by side.
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| The Sonotone Model 700 vacuum tube hearing aid in its original leatherette carrying case. |  | Click picture for larger view | | | |
| Outside view of the Sonotone Model 700 vacuum tube hearing aid's leatherette carrying case. The case measured 6⅝" x 4¼" x 1⅝" (16.8 x 10.4 x 4.1 cm).
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