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 B-7B Carbon Hearing Aid

The Radioear B-7B carbon hearing aid was manufactured by E. A. Myers & Sons, Ltd. of Pittsburg, PA in 1931.

The B-7B transmitter (microphone), shown in the pictures, measured 3⅜" in diameter, while the B-7A (a similar model) was slightly larger measuring 3˝” in diameter.

The carbon transmitter (microphone) plugged onto a battery case that held two “C” size batteries, or it could be plugged directly onto a Radioear battery. The operating voltage was 3 or 4˝ volts depending upon the amount of power required for a given hearing loss.

A small black miniature receiver, onto which an ear mold was clipped, plugged into the transmitter.

Typically, the Model B-7A came with an air conduction receiver, while the Model B-7B came equipped with a bone conduction receiver (although here the B-7B is shown with the air conduction receiver).  

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The front of the Radioear B-7B transmitter (microphone) showing the on-off switch/rheostat volume control (left). It is in the off position. Down all the way would be the loudest volume.

On the right side is a "Tel/Voice" switch. Moving the Tel-Voice switch to the “Tel” position opened up  the 5 screened holes in the centre of the transmitter so that a telephone receiver could be held directly against the carbon transmitter.

When in the “Voice” position, the sound entered the carbon transmitter through the six slots located around the circumference of the transmitter.

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The back of the Model B-7B transmitter with the receiver cord plugged into it (right side).



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