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Desktop Hearing Aid

This late 1930s Zenith hearing aid may seem ancient, but hearing aids have actually been around (in various forms) for hundreds of years. The earliest hearing aids were simply large horns or “ear trumpets”. Sound entered a large horn-like opening, while the smaller end was held in the ear. Variations and improvements on this concept were the only option until around the turn of the 20th century, when the first electrical hearing aids were developed, using carbon microphone technology. However, these devices were rife with problems. They were often large and impractical, their components (a microphone, battery box, processing unit, and headpiece) were often completely separate, their batteries had short life spans, and they could cost as much as $400.

Carbon microphone hearing aids went through improvements as well. There were even wearable versions by the 1930’s. But the invention of vacuum tube technology within processing units shrank hearing aids slightly and made sound much clearer for users of hearing aids. This Zenith Ravox hearing aid is a tabletop model from 1938. It used vacuum tube technology and housed all components, except for the earpiece, in one unit. Rather than using batteries, this unit plugged into an electrical outlet. (Which were still fairly impractical at the time!) A control knob is used to adjust the amplifier in order to emphasize certain frequencies and pitch ranges. The Ravox was cheaper than many earlier models, costing around $30.

Manufacture of tabletop hearing aids continued until improvements in batteries and microphones made them obsolete. These new models combined the microphone, amplifier, and battery into a single unit that could be placed on, or even in the human ear. This allowed for improved hearing and concealment. Today, there are even digital hearing aids that allow for even greater clarity and control of sound. Hearing aid technology has certainly come a long way. From ear trumpets, to tabletop models, to digital earpieces, technology has continued to help hearing aids make life easier for the hearing impaired.

Sources:
http://www.radiomuseum.org/r/zenith_ravox_hearing_aid.html
http://www.pbs.org/wnet/soundandfury/cochlear/hearingaids.html
http://dept.kent.edu/hearingaidmuseum/hearing_aid_eras/pre_electric.htm

* Post prepared by Tyler Jones, WCHC Student Intern.

Dictaphone

Machines like this were used to record speech for playback and transcription. In 1877, Thomas Edison invented an earlier version of this machine that could record and reproduce the human voice. His design used a tinfoil-covered cylinder. When he listed the uses for his invention, ‘letter writing and all kinds of dictation’ was at the top of the list. In 1881, Alexander Graham Bell, Chichester Bell, and Charles Sumner Tainter produced the first recording device that used a rotating wax-coated cylinder. The machine used a steel stylus (needle) to cut vertical grooves in the wax coating in order record sound. By the late 1880’s, Bell and Tainter formed the Volta Gramaphone Co. and began to manufacture sound recording machines specifically for business and office use.

In 1907, the patent was sold to American Gramaphone Co., which eventually became Columbia Gramaphone Co., who trademarked the Dictaphone. In 1923, the Dictaphone Corporation was created from the Columbia Gramaphone Co., and by 1939, the first electronic dictation machines were introduced. Wax cylinders like the one this model were used until the mid 40’s. In 1947, Dictaphone introduced the Dictabelt technology, which cut grooves into plastic belts instead of wax cylinders. This technology was eventually replaced magnetic tape and then hard drive recording, which is most common today. The Dictaphone Corporation entered the digital era in the 1980’s, and still exists today as one of America’s five oldest surviving brands.

Sources:
http://www.officemuseum.com/dictating_machines.htm
http://www.dictaphone.com/aboutus/

* Post prepared by Tyler Jones, WCHC Student Intern.

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