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

Siemens/Fortiphone Model M-22 "Booster Flat" Carbon Hearing Aid

The Siemens/Fortiphone Model M-22 "Booster Flat" carbon hearing aid was made in 1925. The actual hearing aid was made by Siemens & Halske A. G. of Germany, while the resonant black leatherette-covered case was made by Fortiphone Ltd. of London, England. Fortiphone put the hearing aid in the case and sold it under the Fortiphone trade name.

The case measured 7½" x 5¾" x 3¼" deep. The hearing aid and case together weighed just over 1¼ pounds without the battery.

The double carbon microphones measured 4¾" x 2⅜" x 7/16" thick.

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Front view of Siemens/Fortiphone Model M-22 hearing aid microphone showing the on-off switch between the two microphones.

This switch can also be accessed through the hole in the front center of the case when using the hearing aid in the case.


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Back view of Siemens/Fortiphone Model M-22 hearing aid microphone. The black paint is almost all worn off. Engraved on the back just below the leather button hole are the words "Siemens & Halske A. G. Germany"

Near the bottom is the serial number "10957" and the letter "N" below it.


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Front view of Siemens/Fortiphone Model M-22 hearing aid volume control. The black paint is mostly worn off showing its brass construction.


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Back view of Siemens/Fortiphone Model M-22 hearing aid volume control showing the pocket clip.


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Top view of Siemens/Fortiphone Model M-22 hearing aid carbon amplifier. The amplifier plugged directly into a battery.

This hearing aid could use any of the 3 or 4½ volt batteries in use at this time such as the Fortiphone No. 3-S battery.

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Rear view of Siemens/Fortiphone Model M-22 hearing aid carbon amplifier.


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The receiver and stock ear mold of the Siemens/Fortiphone Model M-22 hearing aid.


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View of stock ear mold (left) and receiver of the Siemens/Fortiphone Model M-22 hearing aid. The ear mold snapped into the hole in the receiver.


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The microphone of the Siemens/Fortiphone Model M-22 hearing aid had a leather button-hole attached to the back. This way the microphone could be attached to any button on the wearer's shirt.

Alternately, a black ribbon could be threaded through the button hole and worn as a lanyard around the wearer's neck.


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The Siemens/Fortiphone Model M-22 hearing aid microphone had a swing out "stand" (bottom center) to hold it vertical when placed on a table when it was not being used in its case.


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Bottom view of Siemens/Fortiphone Model M-22 hearing aid microphone showing the stand swung out.


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Bottom view of Siemens/Fortiphone Model M-22 hearing aid microphone showing the swing out stand folded up.


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The Siemens/Fortiphone Model M-22 hearing aid in its original resonant case.


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Outside view of the Siemens/ Fortiphone Model M-22 hearing aid resonant case.

 


 

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