Gem Model 30 Standard "4" Carbon Hearing Aid The Gem Model 30 Standard "4" carbon hearing aid was manufactured by The Gem Ear Phone Co. of New York, NY around 1935. There were a number of early Gem carbon hearing aids. Since Gem didn't put model numbers on these aids, and since there are few, if any, records describing each model, it is impossible to know for sure which model is which. As a result, to differentiate different similar unmarked models in the museum, I have simply given a serial number in quotes (e.g. "4") to these unknown models. Thus this Gem carbon hearing aid is "4" version of what I think is the Gem Model 30 Standard carbon hearing aid. It was a pretty basic unit just consisting of a microphone and an earphone connected by a single cord. This hearing aid was quite heavy for its size, weighing 14.7 oz. (416 g) with the battery (7.2 oz. (204 g) without the battery).
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| Front view of the microphone of the Gem Model 30 Standard "4" carbon hearing aid. The microphone grill consisted of many small holes. The microphone was 2½" in diameter and 1 7/16" thick (6.4 x 3.7 cm). Around the rim of the microphone are the words "Gem Ear Phone Co., N.Y." and "Pat Appl'd For" (Patent Applied For). |  | Click picture for larger view | | | |
| The front of the microphone of the Gem Model 30 Standard "4" carbon hearing aid was surrounded by a donut-shaped "Sound Perfector". This "Sound Perfector" acted like a shield to make this microphone more directional from the front, and thus would seem to enhance the sound of the person you were talking to. |  | Click picture for larger view | | | |
| Rear view of the microphone of the Gem Model 30 Standard "4" carbon hearing aid showing the fiber volume control (black thumb wheel in center). Notice the small hole at the 11 o'clock position showing the volume level (2 in this case). Volume ranged from 1 to 9. At the top of the volume control is a hole for threading a cord through so you could hang the microphone around your neck if so desired.
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| Side view of the microphone of the Gem Model 30 Standard "4" carbon hearing aid showing the raised black fiber volume control wheel. It had a serrated edge for ease of turning.
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| View of the Gem Model 30 Standard "4" carbon hearing aid microphone (left) and battery (right). The pins are of slightly different size so you could only plug them together the right way ensuring the correct polarity. This hearing aid used a Gem 1A 3-volt battery (right). The microphone plugged directly onto the battery.
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Side view of the Gem Model 30 Standard "4" carbon hearing aid. Notice that the prongs on the battery are set near the back instead of the center as was more common. This provided better stability for the hearing aid since the microphone was "front heavy". It also provided for a sleeker-looking hearing aid.
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| Front view of the earphone for the Gem Model 30 Standard "4" carbon hearing aid. The earphone measured 2 1/16" in diameter by 11/16" thick (5.3 x 1.7 cm).
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The earphone was held in place by a headband the snapped into two small holes in the sides of the earphone.
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| Rear view of the Gem Model 30 Standard "4" carbon hearing aid earphone showing the on-off switch on the side (top) with the "On" and "Off" positions shown on the back.
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| The Gem Model 30 Standard "4" carbon hearing aid in its carrying case.
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| The original case for the Gem Model 30 Standard "4" carbon hearing aid was finished in black leatherette. The top of the case reads "The Gem Earphone Co., New York". The case measured 7⅜" x 2¾" x 3⅜" deep (18.8 x 7.0 x 8.6 cm).
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