Electronics World articles Popular Electronics articles QST articles Radio & TV News articles Radio-Craft articles Radio-Electronics articles Short Wave Craft articles Wireless World articles Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors LinkedIn Crosswords Engineering Humor Kirt's Cogitations RF Engineering Quizzes Notable Quotes Calculators Education Engineering Magazine Articles Engineering software RF Cafe Archives Magazine Sponsor RF Cafe Sponsor Links Saturday Evening Post NEETS EW Radar Handbook Microwave Museum About RF Cafe Aegis Power Systems Alliance Test Equipment Centric RF Empower RF ISOTEC Reactel RF Connector Technology San Francisco Circuits Anritsu Amplifier Solutions Anatech Electronics Axiom Test Equipment Conduct RF Copper Mountain Technologies Exodus Advanced Communications Innovative Power Products KR Filters LadyBug Technologies Rigol TotalTemp Technologies Werbel Microwave Windfreak Technologies Wireless Telecom Group Withwave RF Cafe Software Resources Vintage Magazines RF Cafe Software WhoIs entry for RF Cafe.com Thank you for visiting RF Cafe!
Werbel Microwave (power dividers, couplers)

withwave microwave devices - RF Cafe

everythingRF RF & Microwave Parts Database (h1)

Please Support RF Cafe by purchasing my  ridiculously low-priced products, all of which I created.

RF Cascade Workbook for Excel

RF & Electronics Symbols for Visio

RF & Electronics Symbols for Office

RF & Electronics Stencils for Visio

RF Workbench

T-Shirts, Mugs, Cups, Ball Caps, Mouse Pads

These Are Available for Free

Espresso Engineering Workbook™

Smith Chart™ for Excel

DC-70 GHz RF Cables - RF Cafe

Bell Telephone Labs: Test Tube for Sound
December 1947 Radio News

December 1947 Radio News
December 1947 Radio & Television News Cover - RF Cafe[Table of Contents]  These articles are scanned and OCRed from old editions of the Radio & Television News magazine. Here is a list of the Radio & Television News articles I have already posted. All copyrights are hereby acknowledged.

Some people like to demean engineers and scientists for their propensity to want to conduct experiments and obtain measured, empirical data rather than "winging it" and being satisfied with intuitive knowledge or the contemporarily popular term "gut." If mankind had not adopted scientific methods and ventured beyond the so-called cradle of civilization on the African continent, we would all still be living in grass huts, hurling rocks at prey, and foraging for berries. Quantifying and categorizing all things in nature helps inventors create new and improved implements that help make life better. Early on it was mostly individuals like Archimedes, Euler, Newton, and Edison who built the pool of knowledge that fed and evolved into corporations, governments, and universities doing the vast majority of the work. Bell Laboratories is probably one of the most recognizable names for a group of people that collectively produced an immense amount of data and products. This infomercial in a 1947 edition of Radio News is a prime example of the kind of intense, well-planned effort that went into advancing the state of the art of audio communications.

Test Tube for Sound

Test Tube for Sound Bell Labs Advertisement, December 1947 Radio News - RF CafeA telephone listens to a loud speaker in the new "free field" acoustic test room at Bell Telephone Laboratories. The sound-transparent "floor" is built of steel cables.

This giant "test-tube" is actually an echoless sound room at Bell Telephone Laboratories. Here engineers seek new facts about sound which will help them make telephone service still better and more dependable.

Bell scientists know a great deal about what happens to sound in electrical systems. This new room will give them a powerful tool to find out more about what happens to sound in the air.

In an ordinary living room, most of the sound addressed to you comes by way of reflections. At 10 feet less than 10% reaches you directly.

Sound that bounces at you from walls, ceilings, furniture, and your body is all right for hearing - but it poses questions for scientists who would study it uncontaminated by reflections.

The Bell Laboratories "test-tube" gives telephone people the chance to produce pure sound and analyze" it reliably with respect to intensity, pitch, and direction. The entire room is lined with glass wool, contained in wire-mesh cases, wedge-shaped to give maximum absorbing area. Sound bounces along the sloping surfaces, sifts into the soft glass wool, and is gradually stifled.

This is one more example of Bell Laboratories' constant work to learn more about everything which can extend and improve telephone service.

Bell Telephone Laboratories

Exploring and inventing, devising and perfecting for continued improvements and economies in telephone service.



Posted January 25, 2022
(updated from original post on 8/27/2015)

DC-70 GHz RF Cables - RF Cafe
RF Cascade Workbook 2018 by RF Cafe

Anatech Electronics RF Microwave Filters - RF Cafe

Windfreak Technologies Frequency Synthesizers - RF Cafe