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.

 

Transistor (Body) Hearing Aids

Sonotone Model 300X Transistor (Body) Hearing Aid

The Sonotone Model 300X transistor body hearing aid was manufactured by Sonotone Corp in 1965.

The stainless steel case measured 3⅛" by 1⅜" by about 11/16" thick and weighed 3 oz without the batteries. It had a brown plastic insert on the front and a shiny hard brown plastic lower front.

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Top view of the Sonotone 300X transistor hearing aid showing the volume control (left rear), the 13-slot microphone grill (front center) and the 3-position off-on-t-coil switch (right).

This hearing aid may have been the first to have a ceramic microphone.

 

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Left side view of the Sonotone 300X transistor hearing aid showing the "Bi-Focal" switch (upper left of center). It appears this switch set the hearing aid in either regular or high-power mode.

The model 300X was a higher powered version of the model 300.

 

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Close-up of the Sonotone 300X hearing aid receiver cord plug and receiver cord jack (center) showing the 3-prong plug and jack. Sonotone used this 3-prong plug arrangement on both the hearing aid body and the receiver.
 

 

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View of the battery compartment of the Sonotone 300X transistor hearing aid with the batteries removed.

This hearing aid took 2 No. 401 ("N") batteries.

The inside of the battery cover shows the model number and the legend for the bank of 5 tiny controls lying immediately above the upper battery.

These controls are discrete-position sliding switches. On the left is the 2-position "LO" low-pass filter control labeled "2", "1". The second 2-position "LVL" control is label "H", "M". The center 2-position "HI" high-pass filter control is labeled "B", "A". The fourth 2-position "AVC" control (automatic volume control) is labeled "T", "U". On the right is the 3-position "POWER" control labeled "P", "R", "S".

To set them, you put a pen in the hole  and slide the control to the position you want.

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View of the Sonotone 300X transistor hearing aid in its case.

 

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The Sonotone logo on the inside lid of the Sonotone 300X transistor hearing aid case.

 

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Outside view of the case of the Sonotone 300X hearing aid.

 


 

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