Siemens Model 23 Carbon Hearing Aid
The Siemens Model 23 carbon hearing aid was made by Siemens & Halske A. G. of Germany
around 1925.
It appears to be the quad-microphone version of the double-microphone
Siemens M-22 carbon hearing aid.
Unfortunately, the battery cord/ earphone cord and receiver/earmold
are missing, but it is highly likely that these items are quite similar
to these same items on the Siemens Model M-22
which you can see here. It probably also used the same battery, a 4½
volt
Fortiphone No. 3-S battery.
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The front of the Siemens Model 23 carbon hearing aid quad-microphone. Each
microphone grill consisted of an outer circle of 12 diamond-shaped
cut-outs and an inner row of alternating diamond-shaped cut-outs and
small circles. The quad carbon microphone assembly measured 4¼"
square x ⅞" thick. It weighed 7.2 oz.
Note the
leather button-hole (top). This way the microphone could
be attached to any button on the wearer's clothes. Alternately, a ribbon could be threaded through the button hole
so the hearing aid could be worn on a lanyard
around the wearer's neck.
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Rear view of Siemens Model 23 carbon hearing aid microphone. Engraved on the back just below the
leather button hole are the words "Siemens & Halske A. G. Germany"
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Side view of Siemens Model 23 carbon hearing aid microphone showing the
2 jacks for the battery/earphone cord plugs. Quad-microphones provided
more amplification that single or double microphones. Hence, they were
the "power aids" of the day.
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Side view of the Siemens Model 23 carbon hearing aid microphone showing the
foot folded in place for use when wearing it on a lanyard or fastened to
a button.
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Bottom view of the Siemens Model 23 carbon hearing aid microphone
showing the "foot" swung out so it could stand upright on a table
instead of laying flat (see top picture).
It is easy to forget that carbon microphones only worked when held
vertically. When laid down, the carbon shot didn't touch both contacts
on the microphone. Hence no current flowed and the hearing aid didn't
work.
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