How a Microphone Works

1
How a Microphone Works

• Amrita Uttamchandani
• Physics Honors, Period 6
• Project A-9
• Mr. Pagani

2
Alexander 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.

3
Discovery

• Very first discovered by Alexander Graham Bell in
  his telephone transmitter 1876
• First Microphone
• Diaphragm
• Needle and metal foil

4
How Do Microphones Work?

• Goal convert real sound waves into electrical
  audio signals
• Diaphragm vibrates when sound vibrations hit it.
• Electrical current forms

5
...continued...
6
Types

• 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

7
Pickup 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

8
Common Uses

• Tape recorder

9
Common Uses

• Hearing aid

10
The Microphones in a Telephone

• 3 major parts dialing mechanism, transmitter,
  and receiver

11
Bibliography

• 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/t
  ech1.html.
• Microphone. Microsoft Encarta 96 Encyclopedia.
  Microsoft Corp., 1995.
• Microphones. Multimedia Bluffers 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.