The Human Ear

Kall, Maureen

Objectives 1) The student will develop a better understanding of the human ear. 2) The various parts of the ear will be demonstrated using phenomenological apparatus. Equipment and Materials Model of the human ear Clear rubber tubing Funnels Food coloring Balloons Salt Rubber bands Rope Hanger Tape recording of various sounds Nylon Straws (Optional) Shell Slinky (optional) Recommended Strategies Begin the lesson by a quick review of the human senses. Display the model of the human ear and begin to break it down into its various components. Using a rope (or a slinky) demonstrate the motion of sound waves as they enter into the ear. This may be done by having two students volunteer to hold an end of the rope. Have them begin a wave-like motion with the rope and use this demonstration to start a brief discussion on the physical properties of a wave (ie. crest, trough, frequency & wavelength). The next step is to explain the function of the eardrum. This is accomplished by using a funnel apparatus. A balloon should be placed over the large end of the funnel (held taut by using a rubber band). On the small end of the funnel a piece of clear rubber tubing should be attached (straws may be attached to the tubing for hygiene purposes). Grains of salt are then placed on the top of the balloon. Into the rubber tubing, high and low pitched sounds should be made. This demonstrates the vibration of the eardrum by a range of frequencies. The semicircular canals may be shown by molding clear rubber tubing into a circle and filling it approximately half way with colored water. By moving the tubing around the students can be shown the way the semicircular canals are able to balance. A shell may be displayed to show the shape of the cochlea and a hanger molded into a circle and covered with a nylon may be used to demonstrate the oval window. The rubber tubing may then be used again to represent the auditory nerve which leads to the brain. At the end of the demonstration/explanation of the parts of the ear a tape of common sounds may be played. The students will then have to use their listening ability to determine the cause of the sounds that are on the recording.
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