3C10.15 - Ear Drum Model

Code Number:
Demo Title:
Ear Drum Model
Vibration Modes of an Ear Drum
Area of Study:
Acoustics, Biology
Pasco Function Generator, Pail with 3 Inch Hole Connected to a 12 Inch Speaker, Rubber Membrane, Large Rubber Bands, Small Circular Mirror, and Laser Pointer.

Place the rubber membrane over the pail/speaker assembly, stretch it tight, and secure it with a rubber band.  Center and tape the mirror over the hole in the pail.  Orient the laser and the pail / speaker assembly so that the reflection of the laser off the mirror can be easily seen on a screen.  Observe the different vibrational modes on the screen as you sweep the frequencies.  Frequencies between 30 and 150 Hz. work best.  Do not go over 250 Hz. as what you will observe is mostly coupled modes and harmonics.

  • Nicholas P. Truncale and Michelle T. Graham, "Visualizing Sound with an Electro-Optical Eardrum", TPT, Vol. 52, #2, Feb. 2014, p. 76.
  • Brian Andersson and Matthew Dykoski.  "Demonstrating Beats with Springs and a Cart", TPT, Vol. 43, # 8, p. 490, November 2005.
  • 46886 Hand Held Lazer Show, Science Kit & Boreal Laboratories 2000, p. 761.
  • Sara Stein, "Soundscope", The Science Book, p. 180.

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