Deutsche Akustik "Elvau X" Carbon Hearing Aid The Deutsche Akustik "Elvau X" carbon hearing aid was made by Deutsche Akustik-Gesellschaft of Berlin, Germany about 1932. This hearing aid without the battery weighed 7.6 oz (214 g). It consisted of a double carbon microphone, carbon amplifier, receiver and associated cords. Here is the 2-page instruction manual (Gebrauschsanweisung) in German. Here is a 1-page list of 10 rules (Gebote) for using this hearing aid—also in German. |  | Click picture for larger view | | |  | | | |
| View of the Deutsche Akustik "Elvau X" double carbon microphones. This gave this hearing aid more power since the two microphones hooked up in parallel allowed more current to flow. Each microphone is 2½" (6.4 cm) in diameter and 11/16" (1.7 cm) thick.
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| Close-up view of one of the Deutsche Akustik "Elvau X" carbon microphones showing the microphone grill pattern.
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| Side view of the Deutsche Akustik "Elvau X" carbon hearing aid microphone.
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| Rear view of the Deutsche Akustik "Elvau X" double microphone assembly. The two microphones were screwed to a flat plate to keep them together.
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| Rear view of the Deutsche Akustik "Elvau X" carbon hearing aid showing the pocket clip on the back of the "top" microphone.
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| Rear view of the Deutsche Akustik "Elvau X" carbon hearing aid showing the 4-position volume control on the back of the "bottom" microphone. The left-most position is the "off" position.
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| Close-up of the plate holding the two carbon microphones together showing the model number. The inscriptions read, "Original", "Akustik" and "Elvau X".
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| The 3-pronged microphone cord plugged into one end of the Deutsche Akustik "Elvau X" hearing aid's carbon amplifier.
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| Close-up view of the Deutsche Akustik "Elvau X" carbon amplifier with the microphone cord plugged in. The carbon amplifier measured 1 13/16" (4.6 cm) wide by ⅞' (2.3 cm) deep by 1 1/16" (2.2 cm) high.
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| Bottom view of the Deutsche Akustik "Elvau X" carbon hearing aid's carbon amplifier showing the two pins that plugged into the battery. The right pin is larger so you couldn't accidentally plug the amplifier in backwards—thus reversing the polarity of the circuit.
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| The Deutsche Akustik Elvau-X carbon hearing aid was powered by a 4½-volt battery such as this Fortiphone No. 3-S. |  | Click picture for larger view | | | |
| Close-up view of the receiver Deutsche Akustik "Elvau X" carbon hearing aid. It was held in the ear by an wire ear hook that fit in a groove around the circumference of the receiver (missing). |  | Click picture for larger view | | | |
| The back of the ear piece (receiver) of the Deutsche Akustik "Elvau X" carbon hearing aid showing the on position "E" (einschalten) and the off position "A" (ausschalten). The switch is in the off position. This hearing aid was unusual in that there was not just one, but two different on-off switches—this one on the earphone and the other one on the microphone. |  | Click picture for larger view | | | |
| Close-up side view of the ear piece (receiver) showing how the ear tips screwed on/off. |  | Click picture for larger view | | | |
| The Deutsche Akustik "Elvau X" carbon hearing aid came with three ear tips to better fit different sized ear canals. |  | Click picture for larger view | | | |
| Close-up view of the two plugs—one from the microphone and one from the ear piece (receiver). Unlike the plugs of today, each piece had one plug and one socket for the matching one of the other piece. |  | Click picture for larger view | | | |
| The two plugs when plugged together. |  | Click picture for larger view | | | |
| The lid of the box it came with had the following message on it. |  | Click picture for larger view | | | |
| The carrying case for the Deutsche Akustik "Elvau X" carbon hearing aid. It measured 10¼" (26 cm) by 3⅛" (8 cm) by 1⅝" (4 cm) high.
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