1. Have the test subject sit with eyes closed.

2. Pack one of the subject's ears with cotton.

3. Hold a ticking watch close to the open ear and slowly move it straight out and away from the ear.

4. Have the subject indicate when the sounds of the ticking can no longer be heard.

5. Use a meter stick to measure the distance in centimeters from the ear to the position of the watch.

6. Repeat this procedure to test the acuity of the other ear.

7. Record the test results in the data sheets.

USE THIS DATA TABLE TO ENTER YOUR RESULTS

C) Sound Localization

1. Have the subject sit with eyes closed.

2. Hold the ticking watch somewhere within the audible range of the subject's ears and ask the subject to point to the watch.

3. Move the watch to another position and repeat the request. In this manner, determine how accurately the subject can locate the watch when it is in each of the following positions:

         in front of the head
         behind the head
         above the head
         on the right side of the head
         on the left side of the head.
   

4. Record the tests results in the data sheets.

USE THIS DATA TABLE TO ENTER YOUR RESULTS

D) Rinne's Test

1. Obtain a tuning fork and strike it with a rubber hammer, causing it to vibrate.

2. Place the end of the fork's handle against the subject's mastoid process behind one ear. (Have the prongs of the fork pointed downward and away from the ear, and be sure nothing is touching them.)

3. Ask the subject to indicate when the sound is no longer heard.

4. Then, quickly remove the fork from the mastoid process and position it in the air close to the opening of the nearby external auditory meatus.

5. If hearing is normal, the sound will be heard again; if there is conducive impairment, the sound will not be heard.

E) Weber's Test

1. Strike the tuning fork with the rubber hammer.

2. Place the handle of the fork against the subject's forehead in the midline.

3. Ask the subject to indicate if the sound is louder in one ear than in the other or if it is equally loud in both ears.

4. If hearing is normal, the sound will be equally loud in both ears. If there is conducive impairment, the sound will appear louder in the affected ear.

The sense of equilibrium involves two sets of sensory organs. One set functions to help maintain the stability of the head and body when they are motionless and produces a sense of static equilibrium. The other set is concerned with balancing the head and body when they are moved suddenly and produces a sense of dynamic equilibrium.

The organs associated with the sense of static equilibrium are located within the vestibules of the inner ears, while those associated with the sense of dynamic equilibrium are found within the ampullae of the semicircular canals.

Perform the following tests, using a person who is not easily disturbed by dizziness or rotational movement as a test subject. Also have some other students standing close by to help prevent the test subject from falling during the tests. The tests should be stopped immediately if the test subject begins to feel uncomfortable or nauseated.

A) Vision and Equilibrium

Vision and equilibrium. To demonstrate the importance of vision in the maintenance of equilibrium:

Barany's test. To conduct this test:

1. Have the test subject sit on a rotating chair with his or her eyes closed, the head tilted forward about 30º, and the hands gripped firmly to the seat. Be prepared to prevent the subject and the chair from tipping over.

2. Rotate the chair every two seconds for a total of ten rotations.

3. Abruptly stop the movement of the chair.

4. Have the subject open the eyes, and note the nature of the eye move ments and their direction (such eye movements are called nystagmus). Also note the time it takes for the nystagmus to cease.

5. Record your observations in the data sheets.

6. Allow the subject several minutes of rest, then repeat the procedure with the subject's head tilted nearly 90º onto one shoulder.

7. After another rest period, repeat the procedure with the subject's head bent forward so that the chin is resting on the chest.

USE THIS DATA TABLE TO ENTER YOUR RESULTS

In this test, when the head is tilted about 30º, the lateral semicircular canals receive maximal stimulation, and the nystagmus is normally from side to side. When the head is tilted at 90º, the superior canals are stimulated and the nystagmus is up and down. When the head is bent forward with the chin on the chest, the posterior canals are stimulated and the nystagmus is rotary.

1. What is meant by 20/70 vision?

2. What is meant by 20/10 vision?

3. What visual problem is created by astigmatism?

4. Why does the near point of accommodation often increase with age?

5. Explain why an eye has a blind spot.

6. In performing the peripheral monochrome vision exercise, why is the color of the object difficult or impossible to determine?

7. Which are best seen in peripheral vision, black and white or color?

8. Describe what you see in the Holusion Art prints.

9. Describe any differences you find between the right ear and left ear concerning acuity or localization.

10. When the eyes are open, what sensory organs provide information needed to maintain equilibrium?

11. When the eyes are closed, what sensory organs provide such information?

12. In performing the Vision and Equilibrium experiment, did the test subject's unsteadiness increase when the eyes were closed?

13. What is the significance of your observation from the above question (#12)?