How a Microphone WorksHow a Microphone Works

Amrita Uttamchandani

Physics Honors, Period 6

Project A-9

Mr. Pagani

Alexander Graham BellAlexander Graham Bell

Born March 3, 1847 In 1874, he developed the

primitive version of the telephone while working on a multiple telegraph.

Other inventions include moveable section of airplane wing, audiometer, induction balance and a primitive phonograph.

DiscoveryDiscovery

Very first discovered by Alexander Graham Bell in his telephone transmitter; 1876

First Microphone: – Diaphragm– Needle and metal foil

How Do Microphones Work?How Do Microphones Work?

Goal: convert real sound waves into electrical audio signals

Diaphragm vibrates when sound vibrations hit it.

Electrical current forms

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TypesTypes CARBON: carbon

granules and moveable metallic diaphragm that covers the granules

DYNAMIC: thin plastic diaphragm attached to a dense coil of wire that is surrounded by a magnet

CONDENSER: capacitor (two thin metallic plates placed close to each other); back-plate and front-plate, or diaphragm

CRYSTAL: piezoelectric crystals and diaphragm

Pickup PatternsPickup Patterns

OMNI-DIRECTIONAL: picks up sounds from all directions

UNI-DIRECTIONAL: picks up sound from one direction

BI-DIRECTIONAL: picks up patterns from two opposite directions

CARDIOD MICROPHONES: heart shaped pickup pattern– Proximity effect

Common UsesCommon Uses

Tape recorder

Common UsesCommon Uses

Hearing aid

The Microphones in a The Microphones in a TelephoneTelephone

3 major parts: dialing mechanism, transmitter, and receiver

BibliographyBibliography “Bell, Alexander Graham.” Microsoft Encarta 96 Encyclopedia. Microsoft

Corp., 1995. Brodsky, Arthur R. “Telephone.” World Book Online Americas Edition.

http://wwwaolsvc.worldbook.aol.com/wbol/wbpage/na/ar/co/549860.

Ciletti, Eddie (1997). “Microphone Topology.” http://www.tangible-technology.com/microphones/tech1.html.

“Microphone.” Microsoft Encarta 96 Encyclopedia. Microsoft Corp., 1995. “Microphones.” Multimedia Bluffer’s Guides.

http://home1.pacific.net.sg/~firehzrd/audio/mics.html. October 1, 2001. “Question and Answer: Microphones.” (1998-2001).

http://www.howstuffworks.com/question309.htm. September 30, 2001.