Hugh Hetherington Hearing Aid Museum
Hugh Hetherington Hearing Aid Museum

The Hearing Aid Museum

Hearing Aids of all types—Ear Trumpets, Carbon Hearing Aids, Vacuum Tube Hearing Aids, Transistor Hearing Aids, Body Hearing Aids, Eyeglass Hearing Aids and much more!

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Click on the "General Information" button (top button above) for an overview and general information on this category of hearing aid.

 

Carbon Hearing Aids: 1900-1939

Port-O-Phone Model C Carbon Hearing Aid

The Port-O-Phone Model "C" carbon hearing aid was manufactured by the Port-O-Phone Corp of New York, NY in 1915.

The Model "A" was for mild hearing losses, whereas the Model "C" (shown here) was for moderate hearing losses. They also had a Model "M" for severe hearing losses.

The Port-O-Phone Model C measured 3 7/16" x 3 7/16" x 1⅛" (8.7 x 8.7 x 2.9 cm) and weighed 22 oz. (624 g) with everything in the case.

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Front view of the Port-O-Phone Model "C" carbon hearing aid microphone case. Note that the sound entered the case via the holes around the microphone. The center circle is the back of the microphone itself.



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Inside view of the microphone case of the Port-O-Phone Model "C" carbon hearing aid.

 

 

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Close-up view of the microphone of the Port-O-Phone Model "C" carbon hearing aid microphone case. Notice the unusual arrangement of the microphone—it is mounted so that its back is to the sound grill. This way the sound entered the microphone case and had to reflect of the back of the case and into the holes on the microphone itself.

Stephen Porter, the inventor of the Port-O-Phone had a US patent for a backward facing microphone that was supposed to increase the sensitivity of the microphone so it could pick up fainter sounds from a greater distance.

You can read his patent application here. The patent (No. 1,171,460) was filed on June 12, 1915 and granted on Feb 15, 1916.

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Close-up view of the wiring in the microphone case of the Port-O-Phone Model "C" carbon hearing aid.

As you can see, the design of carbon hearing aids was very simple.

The 5 wire coils (bottom center) are the resistance windings for the 6 step volume control (shown in picture below).

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Top view of the Port-O-Phone Model "C" carbon hearing aid microphone case showing the 6-step volume control (top right).

The angle bracket in the center was either for hooking the microphone on a button  on your shirt, or for threading a lanyard through so you could wear the microphone around your neck.

 

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Right side view of the  Port-O-Phone Model "C" carbon hearing aid case showing the attached label.

The label reads "Port-O-Phone", "[Serial] No. 11561" US Patent No. 1171460", "Model C", "Port-O-Phone Corp." "Made in U.S.A.  New York".

 

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Close-up view of the battery connector of the Port-O-Phone Model "C" carbon hearing aid and a battery that it fit. The battery connector just pushed onto the battery pins. One jack was larger than the other so you couldn't plug it in the wrong way.

This hearing aid used a 3 volt carbon-zinc battery such as this Gem No. 1A battery.

 

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The Port-O-Phone Model "C" carbon hearing aid connector shown plugged onto the battery.


 

 

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Front view of the earphone of the Port-O-Phone Model "C" carbon hearing aid. Stamped on the front is "Port-O-Phone" (top) and "Corporation" & "New York, USA" (bottom).

 

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Side view of the earphone of the Port-O-Phone Model "C" carbon hearing aid showing the on-off switch.

The earphone was 2" (5.1 cm) in diameter and ¾" (1.9 cm) thick.

 

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Rear view of the earphone of the Port-O-Phone Model "C" carbon hearing aid showing the positions for the on-off switch.

 

 

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The Port-O-Phone Model "C" carbon hearing aid in its carrying case. Note the name on the inside flap of the lid.

 

 

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Close-up view of the name stamped on the inside of the lid of the Port-O-Phone Model "C" carbon hearing aid.

 

 

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Front view of the Port-O-Phone Model "C" carbon hearing aid in its carrying case.

 

 

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Top outside view of the original Port-O-Phone Model "C" carbon hearing aid carrying case. The carrying case measured 9" long x 5¼" wide x 1½" thick (22.8 x 13.3 x 3.8 cm).

 

 


 

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