Acousticon Model 28 (Silver Seal Symphonic) Carbon Hearing Aid
The Acousticon Model 28 carbon hearing aid was manufactured by the General Acoustic Company,
which later became Dictograph Products, Inc. of New York, NY.
Since the Model 28 came out around Acousticon's 25th anniversary in 1928,
it was also called the "Silver Seal Symphonic" or "Silver Anniversary". In honor of this, the
microphone and volume control were inlaid with a fancy pattern.
The Model 28 was manufactured between 1928 and 1932. It replaced the
Acousticon Model SRB. |
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Front view of the Acousticon Model 28 showing the intricate pattern
on the double carbon microphone.
Note that the microphone grill consisted of 6 slots for each microphone.
This carbon microphone measured 3 3/16" in diameter by 15/16" thick
(8.1 x 2.3 cm).
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The back of the Acousticon Model 28 carbon microphone. The pocket
clip is at the top.
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Close-up of the bottom left side of the Acousticon Model 28 carbon microphone showing the
model number (28).
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Close-up of the bottom right side of the Acousticon Model 28 carbon microphone showing
the battery plugs (left) and the battery jacks on the bottom of the
carbon microphone, and the serial number (right). The microphone
plugs and jacks are all the same size so can be plugged in either way.
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Front view of the Acousticon Model 28 carbon hearing aid microphone
stand. This stand was used when the microphone was not clipped to a
shirt pocket.
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Rear view of the Acousticon Model 28 carbon hearing aid microphone stand
showing the two slots for the microphone jacks to fit into to hold the
microphone vertically.
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Rear view of the Acousticon Model 28 carbon hearing aid microphone stand
showing how the microphone mounted in it.
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Front view of the Acousticon Model 28 carbon hearing aid microphone showing
it mounted in the microphone stand. Note that carbon microphones
wouldn't work if laid flat. They had to be kept more or less vertical.
Thus, if not clipped to a pocket or worn on a lanyard around your neck,
you needed the microphone stand in order to keep it working when set on
a table.
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The Acousticon Model 28 carbon hearing aid used a 3-volt carbon-zinc battery such as this
Acousticon Model 2B battery. The battery
cables plugged into the jacks on the top of the battery. Note the two
sizes of the plugs (larger on the left) and jacks so you couldn't plug them in the wrong way.
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Top view of the Acousticon Model 2B carbon-zinc battery showing the
Acousticon Model 28 hearing aid battery plugs plugged into the positive
jack (left) and the 3-volt jack (right). The "spare" jack was for
obtaining only 1½ volts if you ever wanted less volume.
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In honor of the Acousticon Model 28 "Silver Anniversary" carbon hearing
aid, Acousticon came out with the
Acousticon Model 28 carbon battery. It was identical to the
Acousticon Model 2B battery except for a different "cover".
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Close-up of the front of the Acousticon Model 28 carbon hearing aid volume control. It has the
same intricate pattern on it as is on the microphone.
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Rear view of the Acousticon Model 28 carbon hearing aid volume control showing the on-off
switch in the off position.
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Left side view of the Acousticon Model 28 carbon hearing aid volume control showing the "L"
(loud), "M" (medium) and "S" (soft) positions. The slider (right) in the
"S" (soft) position.
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The Acousticon Model 28 carbon hearing aid came with both a receiver and an earphone.
Shown at the right is a side view of the stock ear mold (left) and the receiver (right).
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Side view of the Acousticon Model 28 carbon hearing aid receiver
(bottom) showing the two nubbins that snapped into the stock ear mold
(above). The nubbins were of unequal diameter and length so they would
only let the receiver snap on in the correct position.
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Close-up view of the bottom of a stock ear mold for the Acousticon Model
28 carbon hearing aid. The two outside holes fitted over the two nubbins
on the receiver. The center hole was the sound bore. |
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The stock ear molds for the Acousticon Model 28 carbon hearing aid came
in left ear and right ear versions. The "R" on the right ear mold is
partially obliterated.
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Close-up front view of the left stock ear mold for the Acousticon Model
28 carbon hearing aid. The "L" indicated this ear mold is for the left
ear, and the "1" is the stock model's size.
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Close-up view of the front of the stock ear mold (left ear) for the
Acousticon Model 28 carbon hearing aid showing the ear tip pulled out.
Presumably, there were multiple sizes of ear tips to fit different sized
ear canals. |
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Rear view of the receiver used with the Acousticon Model 28 carbon
hearing aid. It measured
⅞" in diameter x
½" thick (2.2 x 1.2 cm).
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The Acousticon Model 28 carbon hearing aid also came with a headband and
earphone. This made for hands-free
listening.
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Front view of the earphone for the Acousticon Model 28 carbon hearing
aid. It measured 2 3/16" in diameter x
¾" thick (5.5 x 1.9 cm).
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Rear view of the Acousticon Model 28 carbon hearing aid earphone.
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Side view of the Acousticon Model 28 carbon hearing aid earphone showing the earphone plugs (left) and the
earphone jacks on the bottom of the earphone. The two plugs were slightly
different in size, as are the two jacks, so you have to plug them into the
correct jacks. Note the groove round the periphery of the earphone. The headband
clip slid into this groove . |
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Front view of the earphone of the Acousticon Model 28 carbon hearing aid
showing how the earphone clip on the headband slid into the
groove around the periphery of the earphone. This made for hands-free
listening. |
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Close-up view of the headband and earphone of the Acousticon Model 28 carbon
hearing aid showing the swivel arrangement (left) so the earphone could
lay flat fro storage and swivel to the left or right for use with either
ear. |
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Rear view view of the headband and earphone of the Acousticon Model 28
carbon hearing aid showing the earphone swiveled flat for storage.
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The Acousticon Model 28 carbon hearing aid also had a lorgnette-style
handle if you wanted to hold the earphone up to your ear and not wear a
headband. |
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As with the headband clip, the earphone clip of lorgnette handle of the Acousticon Model 28
carbon hearing aid slid into the groove around the periphery of the
earphone.
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The earphone and lorgnette handle of the Acousticon Model 28 carbon
hearing aid properly attached. The lorgnette handle is shown it its
collapsed position. When collapsed the overall length of the handle
and earphone was 6½" (16.4 cm).
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In its extended position the overall length of the earphone and
lorgnette handle of the Acousticon Model 28 hearing aid measured 12"
(30.3 cm). The handle consisted of 3 sections.
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Inside lid of the Acousticon Model 28 carbon hearing aid carrying case. |
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The Acousticon Model 28 carbon hearing aid and two batteries in its carrying case.
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Outside view of the carrying case for the Acousticon Model 28 carbon hearing aid.
The case measured 8⅛" wide x 7¾" deep by 1⅞" high
(20.9 x 19.2 x 4.8 cm).
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Top view of the Acousticon Model 28 carrying case showing the same
basic elegant silver anniversary design that is on the microphone and
volume control.
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