Acousticon Model RF "Multi-Acousticon" Carbon Hearing Aid
The Acousticon model RF, the Multi-Acousticon, was
one of, if not, the largest carbon hearing aids made.
It was manufactured
by Dictograph Products, Inc. of New York and was marketed between 1910
and 1923. At that time it cost $100.00.
It measures 8" in
height, 6¾" in width and 3½" in depth. It weighs a hefty 3 pounds when
fitted with its battery.
Because the loudness of the early carbon hearing
aids was dependent on the current flow through the earphone,
amplification was controlled by the battery voltage, the resistance of
the carbon microphone(s) and the padding resistors in the step-type
volume control featured on many of the aids. When more amplification was
needed, several carbon microphones could be wired in parallel to increase the
current flow even more.
The Acousticon RF could be used with a 3, 4½ or 6 volt battery.
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Some manufacturers produced carbon hearing aids
with two, three or four carbon microphones wired in parallel. The
Multi-Acousticon had four carbon microphones wired in parallel. They
were arranged in a square pattern (see picture at right).
There was
also a small toggle lever just above the name Multi-Acousticon on the
front of the microphones. (You can see this better in the larger
picture.) This lever appears to somehow dampen the
microphones to reduce the high frequency response.
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The large carrying case not only contained the
carbon microphones, but also housed the battery, the earphone, a
headband, a telescoping handle and a small screwdriver to tighten the
connection terminals.
The volume control was located on the left
side (left bottom).
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Close-up of the volume control showing the 6 steps marked from loud
to soft. The level is shown in the loudest position. |
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The
on-off switch was on the back of the ear phone (near top center—shown in
the off position). |
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The earphone could be attached to a telescoping handle (shown in the
extended position) and held to the ear as needed.
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The handle shown in the collapsed position with the earphone removed. |
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The Acousticon RF also came with a headband that could easily be
attached to the earphone for hands-free listening. |
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Close-up of the screwdriver used for tightening the battery
connectors.
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