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 940 Vacuum Tube Hearing Aid

The Sonotone Model 940 vacuum tube hearing aid was manufactured by Sonotone International, Inc. of  Elmsford, NY in 1950.

The Sonotone Model 940 vacuum tube hearing aid weighed 3.8 oz. (106 g) without the batteries. It measured 3⅞" high x 1 7/16" wide by ¾" thick (9.8 x 3.7 x 2.0 cm). It used 3 vacuum tubes.

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Front view of the Sonotone Model 940 vacuum tube hearing aid showing its design of elegant simplicity. This aid was quite small for a vacuum tube hearing aid.

 

 

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Close-up view of the microphone grill of the Sonotone Model 940 vacuum tube hearing aid. The microphone grill consisted of 8 vertical slots behind the gold-colored pocket clip and four short slots on each "shoulder"

 

 

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Right side view of the Sonotone Model 940 vacuum tube hearing aid showing the 2-hole jack for the optional external microphone.

Note the 4 small slots on the "shoulder" (upper right). These allowed the microphone to pick up sounds from the sides better. There were an additional 4 slots on the other side.

 

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Top view of the Sonotone Model 940 vacuum tube hearing aid showing the on-off/volume control wheel (center). This was the only control on this aid.

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

 

 

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Rear view of the Sonotone Model 940 vacuum tube hearing aid showing the swing up battery compartment door on the bottom half.

 

 

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Close-up view of the bottom of the Sonotone Model 940 vacuum tube hearing aid showing the serial number (71016) (left) and the thumb-tab for opening the battery compartment door (center).

 

 

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View of the empty battery compartment of the Sonotone Model 940 vacuum tube hearing aid.

 

 

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Close-up view of the battery compartment of the Sonotone Model 940 vacuum tube hearing aid showing the 15 volt "B" battery (Eveready No. 504E) (left) and the 1.4 volt mercury "A" battery (Mallory No. RM-1) (right).

 

 

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Close-up view of the inside of the lid of the battery compartment of the Sonotone Model 940 vacuum tube hearing aid showing the make (Sonotone) and the model number (940) and the correct placement and polarity of the 2 batteries..

 

 

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Left side view of the Sonotone Model 940 vacuum tube hearing aid showing the receiver cord plugged in.

 


 

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Close-up view of the left side of the Sonotone Model 940 vacuum tube hearing aid showing the receiver cord unplugged.

 

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Edge view of the receiver and receiver cord plug of the Sonotone Model 940 vacuum tube hearing aid showing the receiver cord unplugged.

 

 

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Rear view of the receiver for the Sonotone Model 940 vacuum tube hearing aid showing the receiver cord plugged in.

 

 

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Side view of the receiver and ear mold for the Sonotone Model 940 vacuum tube hearing aid showing how they snapped together.

 

 

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Front view of the receiver of the Sonotone Model 940 vacuum tube hearing aid showing it unsnapped from the ear mold (left).

 

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The Sonotone Model 940 vacuum tube hearing aid in its original carry case.


 

 

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View of the inside of the lid of the carry case of the Sonotone Model 940 vacuum tube hearing aid showing the Sonotone inscription "Sonotone" and "The house of hearing".

 

 

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Outside right front corner view of the Sonotone Model 940 vacuum tube hearing aid carrying case showing the Sonotone name.
 

 

 

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View of the original carry case of the Sonotone Model 940 vacuum tube hearing aid.

 

 

 


 

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