File:Vacuum tube hearing aid use 1933.jpg
Summary
Illustration on the cover of an electronics magazine of use of the first mass market <a href="https://en.wikipedia.org/wiki/vacuum_tube" class="extiw" title="en:vacuum tube">vacuum tube</a> <a href="https://en.wikipedia.org/wiki/hearing_aid" class="extiw" title="en:hearing aid">hearing aids</a> in 1933. Amplifying hearing aids, made possible by the invention of the <a href="https://en.wikipedia.org/wiki/triode" class="extiw" title="en:triode">triode</a> vacuum tube by <a href="https://en.wikipedia.org/wiki/Lee_De_Forest" class="extiw" title="en:Lee De Forest">Lee De Forest</a> in 1906, had just come on the market a few years before, and were a great improvement over previous crude electric hearing aids that used the amplifying ability of a <a href="https://en.wikipedia.org/wiki/carbon_microphone" class="extiw" title="en:carbon microphone">carbon microphone</a>. The hearing aid consisted of a box about the size of a loaf of bread, with a built-in microphone, that the user directed toward the speaking person, with a plug-in headphone. The illustration shows two hearing-impaired men using the hearing aids on a train. Alterations to image: Cropped out extraneous text on the cover.
Licensing
Lua error in package.lua at line 80: module 'strict' not found.
File history
Click on a date/time to view the file as it appeared at that time.
| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 13:24, 5 January 2017 | | 1,194 × 788 (190 KB) | 127.0.0.1 (talk) | Illustration on the cover of an electronics magazine of use of the first mass market <a href="https://en.wikipedia.org/wiki/vacuum_tube" class="extiw" title="en:vacuum tube">vacuum tube</a> <a href="https://en.wikipedia.org/wiki/hearing_aid" class="extiw" title="en:hearing aid">hearing aids</a> in 1933. Amplifying hearing aids, made possible by the invention of the <a href="https://en.wikipedia.org/wiki/triode" class="extiw" title="en:triode">triode</a> vacuum tube by <a href="https://en.wikipedia.org/wiki/Lee_De_Forest" class="extiw" title="en:Lee De Forest">Lee De Forest</a> in 1906, had just come on the market a few years before, and were a great improvement over previous crude electric hearing aids that used the amplifying ability of a <a href="https://en.wikipedia.org/wiki/carbon_microphone" class="extiw" title="en:carbon microphone">carbon microphone</a>. The hearing aid consisted of a box about the size of a loaf of bread, with a built-in microphone, that the user directed toward the speaking person, with a plug-in headphone. The illustration shows two hearing-impaired men using the hearing aids on a train. Alterations to image: Cropped out extraneous text on the cover. |
- You cannot overwrite this file.
File usage
The following page links to this file:
