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

Sonotone Model 451 Carbon Hearing Aid

The Sonotone Model 451 carbon hearing aid was manufactured in 1937 by Sonotone International, Inc. of New York.

This Sonotone microphone was made out of faux tortoiseshell and was a beautiful translucent reddish color, especially with the light shining through it.

This hearing aid without the battery weighed 7.7 oz (218 g).

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Front view of the Sonotone Model 451 carbon hearing aid microphone. This microphone measured 3" (7.5 cm) in diameter and 1¼" (2.9 or 3.1 cm) thick (which was unusually thick for a microphone.



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Close-up view of the center of the Sonotone Model 451 carbon microphone showing the Sonotone "S" logo surrounded by a ring of 12 small microphone holes.

The main entrance for sounds going into the microphone wasn't these small holes, but slots around the circumference of the microphone (see below).

 

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Close-up of the side of the Sonotone Model 451 carbon microphone showing the microphone slots around the periphery of the microphone. They are immediately above the volume control slider knob.

The earphone and battery cables plugged into the 3 pin socket at the bottom (shown unplugged).

 

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Close-up of the bottom front of the Sonotone Model 451 microphone showing the sliding volume control and on-off switch. Off was to the left.
 

 

 

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Rear view of the Sonotone Model 451 carbon hearing aid microphone showing the pocket clip (top).

In the center the inscriptions read, "Sonotone", "Reg. U.S.P.O.", "U.S. Pat. No. 1811638". In the center is the serial number "178404" and below it, "Other Pats. Pend." then "Made in U.S.A." and "New York".
 

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Top view of the Sonotone Model 451 carbon hearing aid carbon amplifier showing the battery/earphone cable plugged in (right).

This carbon amplifier was heavy for its size at 2.3 oz (66 g).

 

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View of the Sonotone Model 451 carbon hearing aid carbon amplifier showing the three-pin battery/earphone plug and socket.


 

 

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Side view of the Sonotone Model 451 carbon hearing aid carbon amplifier showing the two pins on the bottom that plugged directly into a battery such as the Sonotone Model X42 3-volt battery.
 

 

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Bottom view of the Sonotone Model 451 hearing aid carbon amplifier

On the bottom it reads, "Pat. 2046738" and "Pat. Re. 19246".
 

 

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Close-up of the bone-conduction transducer showing the pins and sockets (unplugged).

 

 

 

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View of the back of the Sonotone Model 451 carbon hearing aid bone-conduction transducer with the cords plugged in and also mounted on the headband.

The pins pulled out to replace the cord or transducer if necessary.

 

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Headband of the Sonotone Model 451 carbon hearing aid receiver with bone-conduction transducer attached.


 

 

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View of the Sonotone Model 451 carbon hearing aid in its carrying case.


 

 

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View of the inside of the carrying case lid with the faint inscription, "Sonotone Audicle". The line below reads, "Reg. U.S. Pat. Off.".

 

 

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The carrying case of the Sonotone Model 451 carbon hearing aid.

The case measured 6" (15.3 cm) x 4¾" (12.0 cm) x 2" (2.5 cm).

 

 



 

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