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.