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.

 

Eyeglass Style Transistor Hearing Aids: 1954-1990

Bosch Model 55F Transistor Eyeglass Hearing Aid

The Bosch Model 55F eyeglass hearing aid (also called the Star 55F) was manufactured by Robert Bosch Elektronik GmbH of Berlin, Germany in 1981.

It was rather unusual for its time in that it could be configured as a hearing aid with all the electronics in one temple-piece, or it could be configured so the microphone was contained in the opposite temple-piece to reduce feedback when used in its high-powered settings.

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Front view of the Bosch Model 55F eyeglass hearing aid. The hearing aid electronics are in the left temple-piece and the microphone is in the right temple-piece.

 


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Front view of the Bosch Model 55F eyeglass hearing aid with the temple pieces folded for storage.

 

 

 

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Underside view of the left temple-piece of the Bosch Model 55F eyeglass hearing aid showing the serial number—very faintly stamped into the case below the model no. (55F).

The serial number is very difficult to read but appears to be "931...08".


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Bottom view of the left temple piece of the Bosch Model 55F eyeglass hearing aid showing the various controls.

To the left of the model number (55F) is a recessed screwdriver-accessible control—presumably for adjusting maximum gain. Next to it is the 1-4 position volume control; the tone control (TC) with "high" (H) to the left and "normal" "N" to the right; the 3-position "off" (O), "t-coil" (T) and "microphone" (M) switch shown in the off position; the "dummy" (in this case) domed microphone grill; and the plug for the wire coming from the other temple-piece.

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Close-up view of the bottom front of the left temple piece of the Bosch Model 55F eyeglass hearing aid showing the above-mentioned last four items in greater detail.

Note that in this particular model, there is no microphone below the microphone grill as it uses the microphone built into the opposite temple-piece.

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Close-up bottom view of the electronics module in the left temple piece of the Bosch Model 55F eyeglass hearing aid showing the various components including the volume control wheel (center).


 

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Close-up top view of the electronics module in the left temple piece of the Bosch Model 55F eyeglass hearing aid showing the various components including the volume control wheel (left of center).


 

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View of the bottom of the left temple piece of the Bosch Model 55F eyeglass hearing aid showing the thick temple piece with the ear mold attached to the nubbin.



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Inside rear view of the electronics module of the left temple piece of the Bosch Model 55F eyeglass hearing aid showing the receiver—the transducer that produces the sound (right) and below it the nubbin with the ear mold tube slid onto it.


 

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Inside top view of the left temple-piece of the Bosch Model 55F eyeglass hearing aid showing the space reserved for the microphone IF this aid was to be configured so it only used one temple-piece. (Note the microphone grill holes at the back. Also, note that the microphone shown below in the opposite temple-piece would fit exactly into this space.)
 

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Bottom view of the right temple piece of the Bosch Model 55F eyeglass hearing aid showing the microphone port (left). The dome-shaped microphone grill is missing (but it would look identical to the microphone grill on the left temple-piece). The name "Bosch"  is to the right.


 

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Bottom inside view of the right temple piece of the Bosch Model 55F eyeglass hearing aid showing the cream-colored rectangular microphone directly above the microphone port.


 

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Top inside view of the right temple piece of the Bosch Model 55F eyeglass hearing aid showing the cream-colored rectangular microphone (left) and how it was wired to the mounting post (right). To the extreme right is the wire that runs to the left temple-piece.


 

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Close-up view of the hinge of the left temple-piece of the Bosch Model 55F eyeglass hearing aid showing the wire from the microphone that crossed over from the right temple-piece.

 


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Close up view of the nose bridge of the glasses of the Bosch Model 55F eyeglass hearing aid showing the wire going from the right to the left temple-piece.


 

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Top view of the glasses of the Bosch Model 55F eyeglass hearing aid showing the wire (thin black line) above the lens going from the right temple-piece to the left one.


 

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Rear view of the Bosch Model 55F eyeglass hearing aid.
 

 

 

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Bottom view of the end of the left temple piece of the Bosch Model 55F eyeglass hearing aid showing the name (Bosch) and the location where this hearing aid was made (Germany).

Actually, both temple-pieces have the name on them. Both temple-pieces are identical inside so the electronics modules could be mounted in either of them depending on whether you needed a hearing aid in your left or right ear.

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Close-up view of the tip of the left temple piece of the Bosch Model 55F eyeglass hearing aid showing the battery compartment door in the open position. The battery door swung up from the bottom.

 

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Close-up view of the tip of the left temple piece of the Bosch Model 55F eyeglass hearing aid showing the battery in the battery compartment. This hearing aid took a 675 mercury battery.

Note that the right temple-piece had a similar "dummy" compartment for carrying a spare battery.

 


 

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