1. Amrita Uttamchandani Physics Honors, Period 6 Project A-9 Mr. Pagani
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.
Ciletti, Eddie (1997). “Microphone Topology.”
“Microphone.” Microsoft Encarta 96 Encyclopedia. Microsoft Corp., 1995.
“Microphones.” Multimedia Bluffer’s Guides. October 1, 2001.
“Question and Answer: Microphones.” ( ). September 30, 2001.