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.


Carbon Hearing Aids: 1900-1939

Radioear "Masterpiece" Carbon Hearing Aid

The Radioear "Masterpiece" carbon hearing aid was manufactured by E. A. Myers of Pittsburg, Pennsylvania (later Radioear Corp.) beginning in May of 1939.

The complete unit consisted of a carbon amplifier (top center), battery box (center), receiver (left—ear mold not shown) and microphone (right). Apart from the receiver, the various pieces were made of black bakelite.

With the amplifier attached the battery box and amplifier together measured 5" x 2 9/16" x 1 3/16".

The whole unit (all pieces) including batteries weighed 10 oz.

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The Radioear Masterpiece microphone was 2⅞" in diameter. It was a carbon shot microphone—you can hear the shot rattle when you shake it.

There are four tiny holes—2 near the top and 2 near the bottom. If you look closely, you can see the holes situated between the 2nd and 3rd lines on the front of the microphone. Their purpose is unknown.

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Top view of the Radioear Masterpiece microphone showing the on-off/volume control slider switch. Sliding the switch to the left (right side in picture) turns it off and sliding to the right (left side of picture) increases the volume.

The larger slots around the circumference of the microphone (left and right sides) are where the sound entered.

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A close up of the back of the Radioear Masterpiece microphone. The clip at the top was so you could clip the microphone to your pocket instead of having to hold it.

Note the two position control (lower center). It's function is unknown.


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The carbon granule amplifier (left) plugged directly into the battery box (right).


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In turn, the microphone and earphone plugged into the carbon amplifier. The earphone leads plugged into the two top holes, while the 3-pronged microphone plug, plugged into the 3 bottom holes. (Notice the spacing between the second and third holes so you couldn't plug the microphone in the wrong end by mistake.) Also the top and bottom holes are smaller than the others, again making it impossible to plug things in wrong.

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The carbon amplifier (right) unplugged from the battery box showing the relative size of both.


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The battery box with 3 "C" size (No. 935) regular flashlight batteries in it.

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The empty battery box showing the battery contacts. The Masterpiece ran on 4½ volts (3 1½ volt batteries hooked in series).


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The end of the battery box showing how the amplifier jack connected directly to the batteries.



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