Acousticon Model A-45 Vacuum Tube Hearing Aid The Acousticon Model A-45 was a "Teardrop" shaped, two vacuum tube, two-piece hearing aid. It was made from 1940 to 1942 by the Dictograph Corporation of New York. The overall measurements are 4¼" by 2½" by 1" deep. This is one of the earliest Acousticon vacuum tube hearing aids produced by the Dictograph Corporation. The two top pictures show bone conduction transducers. |  | Click picture for larger view | | |  | | | |
| Another view of the Acousticon Model 45 showing the bone conduction transducer on the headband. The transducer was placed on the bump behind your ear where it vibrated your skull to transmit sound from the hearing aid to the inner ear. Bone conduction was quite popular in the 1930s and 1940s perhaps for a couple of reasons. First, more people may have had conductive losses than today as conductive losses are readily treated now. Second, these early hearing aids didn't have the amplification needed to push a signal through a clogged up middle ear like modern aids can—hence the bone conduction transducer bypassed the clogged middle ear and sent the signal straight to the inner ear. |  | Click picture for larger view | | | |
| The Acousticon Model 45 with the front cover removed so you can see its insides. You can't see the two miniature vacuum tubes as they are hidden by the big round microphone. However, you can see the wires (pins) coming from the base of these tubes at 4 o'clock and 8 o'clock in relation to the microphone disc. |  | Click picture for larger view | | | |
| This hearing aid could be used with either a 30 volt or a 45 volt battery depending on the person's hearing loss. The higher voltage gave greater amplification for more severe hearing losses. The Eveready "B" battery at the right is a 45 volt battery. The two pictures at the right show the Acousticon A-45 with air conduction receivers. |  | Click picture for larger view | | | |
| A view of the Acousticon A-45 showing showing it hooked up to a set of its batteries. The round battery is the standard 1.5 volt "D" cell that provided the filament voltage to the vacuum tubes, while the rectangular red (war) battery is a 30 volt battery to provide the "plate" voltage of the vacuum tubes. The two-pronged plug plugged into the "A" battery while the three-pronged plug was for the "B" battery. |  | Click picture for larger view | | | |
| The original box the Acousticon Model 45 came in.
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