The Sonotone 1010 hearing aid

Hearing aid

A hearing aid is an electroacoustic device which typically fits in or behind the wearer's ear, and is designed to amplify and modulate sound for the wearer. Earlier devices, known as "ear trumpets" or "ear horns", were passive funnel-like amplification cones designed to gather sound energy and...

, introduced on 29 December 1952, was the first commercial product to use transistor

Transistor

A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...

s, which had been invented five years earlier in 1947.

It was a hybrid design, using two miniature vacuum tubes as input stages and a single transistor as the output stage; this was required because the transistors at the time produced too much electrical noise. Even using one transistor considerably extended battery life, lowering the operating cost of the unit. As transistors improved, this model was replaced by all-transistor hearing aids.

The Sonotone company had its headquarters in New York

New York

New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...

and was established in 1929. The company was bought by various other companies and was no longer in business by 2005.