Hugh Hetherington Hearing Aid Museum
Hugh Hetherington Hearing Aid Museum

The Hearing Aid Museum

Hearing Aids of all types—Ear Trumpets, Carbon Hearing Aids, Vacuum Tube Hearing Aids, Transistor Hearing Aids, Body Hearing Aids, Eyeglass Hearing Aids and much more!

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Click on the "General Information" button (top button above) for an overview and general information on this category of hearing aid.

 

Vacuum Tube Hearing Aids: 1921-1953

Sonotone Model 966 Vacuum Tube Hearing Aid

The Sonotone Model 966 vacuum tube hearing aid was manufactured by Sonotone International, Inc. of  Elmsford, NY in 1950.

The Sonotone Model 966 vacuum tube hearing aid weighed a hefty 7.1 oz. (202 g) without the batteries. It measured 4¾" high x 2 7/16" wide by 1" thick (12.0 x 6.2 x 2.5 cm).

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Front view of the Sonotone Model 966 vacuum tube hearing aid. This rather plain hearing aid had a "secret" claim to fame. It was one of the most powerful wearable vacuum tube hearing aids ever produced.

 

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Top view of the Sonotone Model 966 vacuum tube hearing aid showing the on-off switch (left), volume control (center) and the slot containing the receiver cord jack (right).

Note the "S" (for Sonotone) in the center of the volume control.

 

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Close-up view of the top left corner of the Sonotone Model 966 vacuum tube hearing aid  showing the 3-position on-off switch.

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) (shown) . In this position it "dimmed out"  background sounds for clearer hearing in crowded, noisy places".
 

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Close-up view of the top right corner of the Sonotone Model 966 vacuum tube hearing aid  showing the recessed two-pronged receiver cord jack.

 

 

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Close-up view of the gold-colored pocket clip on the upper front of the Sonotone Model 966 vacuum tube hearing aid. The microphone grill is hidden behind the upper part of the clip.

 

 

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Close-up view of the microphone grill of the Sonotone Model 966 vacuum tube hearing aid. The grill consisted of 4 rectangular holes hidden beneath the pocket clip.

 

 

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Rear view of the Sonotone Model 966 vacuum tube hearing aid showing the swing up battery compartment door on the bottom half.

 

 

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Close-up view of the top rear of the Sonotone Model 966 vacuum tube hearing aid with the back cover removed showing the the various adjustments that could be made to this aid.

Through the plastic "window" you could see all 6 of the vacuum tubes used in this hearing aid.

 

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Close-up view of the upper rear of the Sonotone Model 966 vacuum tube hearing aid with the back cover and plastic shroud removed showing the 6 vacuum tubes arranged side by side.

Note: only two wearable (body-style) vacuum-tube hearing aids were ever made using 6 vacuum tubes. The other one was the Aurex Model RX-6 made in 1952.

 

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Close-up view of the center of the left side of the Sonotone Model 966 vacuum tube hearing aid showing the recessed two-pronged jack (most likely for use with a large external "A" battery). This was useful since the "A" battery drained quite fast (as compared to the "B" batteries). Thus if you typically were sitting in one place for extended periods, using the external "A" battery made sense.

 

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Close-up view of the bottom of the Sonotone Model 966 vacuum tube hearing aid showing the serial number (754679) and below it the thumb-tab for opening the battery compartment door.

 

 

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Close-up view of the inside of the lid of the battery compartment of the Sonotone Model 966 vacuum tube hearing aid showing the make (Sonotone) and the model number (966).

 

 

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Inside view of the empty battery compartment of the Sonotone Model 966 vacuum tube hearing aid. An unusual feature of this hearing aid was that it took 1 "A" battery, but 2 "B" batteries.

The two 22½ volt "B" batteries were hooked in series to produce 45 volts in order to give more power. They ingeniously used two 22½ volt batteries because 45 volt batteries were too large to fit into a body aid so were only used in two-piece (external battery) hearing aids.

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Close-up view of the battery compartment of the Sonotone Model 966 vacuum tube hearing aid showing the 1½ volt "A" battery (Eveready No. 1015E) and the two 22½ volt "B" batteries (Eveready No. 505E)

 

 

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Bottom view of the Sonotone Model 966 vacuum tube hearing aid showing a slot in the case for the cord for use with an external "A" battery. However, the design of the battery compartment precluded using this for the external "A" battery cord as the "A" battery was set at the back instead of at the front. Hence the  external battery jack on the left side, but someone forgot to eliminate the "hole" in the bottom.

 

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Close-up of the bottom of the Sonotone Model 966 vacuum tube hearing aid showing the extraneous "hole" for the cord for an external battery when the battery compartment door was closed.

 

 


 

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