Sonotone Model 988 Vacuum Tube Hearing Aid The Sonotone 988 was reputed to be the slimmest and lightest vacuum tube hearing aid ever manufactured. It weighed just over 3 oz. It measured 3.0" high x 1¾" wide by ⅝" thick. The Sonotone Model 988 was manufactured by Sonotone International, Inc. of Elmsford, NY in 1952. As it happened, this was only months before the first transistorized hearing aids came out and made vacuum tube hearing aids obsolete. |  | Click picture for larger view | | |  | | | |
| The Sonotone 988 shown with its back taken off. It used a No. 401 mercury cell for the A battery (left), and a No. 504 15 volt battery for the B battery.
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| The inside of the Sonotone 988 showing the front of the circuit board and the tiny tubes it used. Incidentally, Sonotone made their own tiny vacuum tubes and miniature components. |  | Click picture for larger view | | | |
| The inside of the Sonotone 988 showing the back of the circuit board. |  | Click picture for larger view | | | |
| The Sonotone 988 in its original box. If you are interested, read the news item on the Sonotone 988 that was printed in the New York Times on December 12, 1952.
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