Tuesday, April 12, 2011

Ears and Microphones - Both are Sound Receivers ! - AWARD Opportunity

Your eardrum is a piece of skin just like a stretched balloon. It vibrates when sounds reach your ear. Bones that touch the eardrum carry the vibrations to your inner ear, where they are detected and translated into signals to the brain. Here is a diagram of the ear. Can you explain why sounds aren't as loud when you cover your ear?

A microphone is very much like an ear. Sounds make a surface vibrate, which moves a magnetic coil that produces electrical signals. Those signals are then sent to an amplifier or stereo receiver.  Here is a diagram of a microphone.

Here is a diagram of a loudspeaker. It's like an ear working backwards. (It's also like a microphone working backwards.)  It changes electrical signals into sound vibrations. How does it look like an eardrum? How does the loud speaker work like an ear in reverse?

To receive your award, answer the following by class on Friday:

  • The eardrum is also called the _______________ membrane.
  • When you play a drum, the resulting sound is because the drum head (the surface of the drum that you strike) is _______________. 
  • In 1924, two General Electric researchers patented a design for the modern loudspeaker.  What were the names of these two scientists?
  • It can be difficult to design a single size speaker that can handle a large range of sounds.  Many stereo systems use one size speaker to produce low sounds, another size to produce mid-range and still another to produce high sounds.  Name one of these special types of speakers.
Thanks to Concord Consortium and TEEMSS2 Website: http://portal.teemss2.concord.org/content/texas_instruments_cbl2/analysis_invid_11.html