Siemens/Phonophore Model 45 "Universal" Carbon Hearing Aid The Siemens/Phonophore Model 45 "Universal" carbon hearing aid was made by Siemens & Halske A. G. of Germany around 1930. This basic hearing aid could come configured with a receiver (Model 41), earphone (Model 42), earphone and receiver (Model 43), bone conductor and with a carbon amplifier (Model 45). The Model 45 was also called the "Sonomax". |  | Click picture for larger view | | |   | | | |
| Front view of the Siemens/Phonophore Model 45 carbon hearing aid showing the double carbon microphones. This microphone case measured 5¼" x 2¾" x ⅝" and weighed 7¾ oz.
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| The back of the microphone shows the name of the manufacturer, namely Siemens & Halske A-G, of Germany.
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| Left side view of the Siemens/Phonophore Model 45 carbon hearing aid microphone showing the on-off switch, labeled "ein" or "on" and "aus" or "off". This hearing aid was meant to be sold in Germany (or German speaking areas) as all the controls are labeled in German.
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| Right side view of the Siemens/Phonophore Model 45 carbon hearing aid microphone showing the volume control labeled "laut" or "loud" and "leise" or "soft". To the right of the volume control is the folded up microphone "stand".
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| This microphone "stand" could be folded out so the microphone would be tipped up from any flat surface. Since the microphone is facing down, this arrangement used the table-top as a sound reflecting surface to reflect the sound into the microphones.
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| Alternately, the Siemens/Phonophore Model 45 carbon hearing aid came with a flat spring clip so the microphone could be stood up at right angles to the table to better catch any sounds.
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| Bottom view of the Siemens/Phonophore Model 45 carbon hearing aid microphone showing the sockets for the two cables. Since the holes were all the same size, they were color coded to ensure the plugs were inserted correctly.
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| Bottom view of the Siemens/Phonophore Model 45 carbon hearing aid microphone showing the 3-pronged battery plug (left) and the 2-pronged bone conductor plug (right). To plug them in correctly, you first needed to plug in the battery plug, matching its pins to the color-coding on the microphone, then the bone-conductor plug went into the two remaining holes.
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| The carbon amplifier of the Siemens/Phonophore Model 45 carbon hearing aid. The amplifier plugged directly into the battery and the 3-pronged plug plugged into the side of the carbon amplifier. This hearing aid used 4.5 volt carbon-zinc batteries such as the Siemens? X43/R656 or the Fortiphone 3-S.
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| Bottom view of the carbon amplifier showing the Siemens & Halske logo above the word "Germany".
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| Instead of an earphone, the Siemens/Phonophore Model 45 carbon hearing aid used a bone conductor that was placed on the mastoid bone behind the ear. The headband easily snapped into the two depressions on each side of the bone conductor transducer.
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| View of the headband, bone conduction transducer and cord of the Siemens/Phonophore Model 45 carbon hearing aid.
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| The microphone of the Siemens/Phonophore Model 45 carbon 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, jacket or coat if they so wanted.
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| Alternately, the microphone and battery could be placed in the cloth bag and hung around the wearer's neck.
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| The Siemens/Phonophore Model 45 "Universal" carbon hearing aid in its original case.
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| Outside view of the Siemens/Phonophore Model 45 carbon hearing aid case.
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