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. | ![](../../../../images/photos/275x206/carbon/siemensm22M.jpg) | Click picture for larger view | | | | |
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.
| ![](../../../../images/photos/275x206/carbon/siemensm22switchM.jpg) | Click picture for larger view | | |
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.
| ![](../../../../images/photos/275x206/carbon/siemensm22backM.jpg) | Click picture for larger view | | |
Front view of Siemens/Fortiphone Model M-22 hearing aid volume control. The black paint is mostly worn off showing its brass construction.
| ![](../../../../images/photos/275x206/carbon/siemensm22volM.jpg) | Click picture for larger view | | |
Back view of Siemens/Fortiphone Model M-22 hearing aid volume control showing the pocket clip.
| ![](../../../../images/photos/275x206/carbon/siemensm22volbackM.jpg) | Click picture for larger view | | |
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. | ![](../../../../images/photos/275x206/carbon/siemensm22ampM.jpg) | Click picture for larger view | | |
Rear view of Siemens/Fortiphone Model M-22 hearing aid carbon amplifier.
| ![](../../../../images/photos/275x206/carbon/siemensm22ampbackM.jpg) | Click picture for larger view | | |
The receiver and stock ear mold of the Siemens/Fortiphone Model M-22 hearing aid.
| ![](../../../../images/photos/275x206/carbon/siemensm22rcvrM.jpg) | Click picture for larger view | | |
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.
| ![](../../../../images/photos/275x206/carbon/siemensm22moldM.jpg) | Click picture for larger view | | |
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.
| ![](../../../../images/photos/275x206/carbon/siemensm22buttonM.jpg) | Click picture for larger view | | |
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.
| ![](../../../../images/photos/275x206/carbon/siemensm22standM.jpg) | Click picture for larger view | | |
Bottom view of Siemens/Fortiphone Model M-22 hearing aid microphone showing the stand swung out.
| ![](../../../../images/photos/275x206/carbon/siemensm22bottomM.jpg) | Click picture for larger view | | |
Bottom view of Siemens/Fortiphone Model M-22 hearing aid microphone showing the swing out stand folded up.
| ![](../../../../images/photos/275x206/carbon/siemensm22foldedM.jpg) | Click picture for larger view | | |
The Siemens/Fortiphone Model M-22 hearing aid in its original resonant case.
| ![](../../../../images/photos/275x206/carbon/siemensm22inboxM.jpg) | Click picture for larger view | | |
Outside view of the Siemens/ Fortiphone Model M-22 hearing aid resonant case.
| ![](../../../../images/photos/275x206/carbon/siemensm22boxM.jpg) | Click picture for larger view | |
(If a larger picture doesn't appear, you may have to
turn your pop-up blocker off)
|
| |