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.


Hearing Aid Batteries

Sonotone X42 Hearing Aid Battery

This is a 3-volt Sonotone X42 battery that fit a number of carbon hearing aids in the 1930s and 1940s. It weighed 10½ oz., and measured 4⅛" by 2¼" by 1⅛". As you can faintly see on the front, it is date-stamped Jan. 11, 1945.

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Top view of the Sonotone X42 battery showing the 3-hole socket. Only the 1st and 3rd holes were actually used.

If you look closely, you can see that the plastic covering the center hole has not been punctured. The reason for this is that this battery was either used in a carbon hearing aid that had a carbon amplifier, or a carbon hearing aid that only used two pronged plugs.

Carbon amplifiers only had 2-pronged plugs. Plain carbon hearing aids (without amplifiers) sometimes had 3-pronged plugs. The 3-pronged plug normally plugged into the amplifier, and the 2-pronged amplifier plugged into the battery.

However, you could use the plain carbon hearing aid without the amplifier. In this case, and if the hearing aid had 3-prongs, you plugged the 3-pronged plug directly into the battery—hence you needed a center (dummy) hole in the battery, even though only the 1st and 3rd holes were actually used.

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