: - 1 I'; t : " \ t : -. ^ : EXERCISE 95 



Problem. Do the two ears of a person differ from each other in acuteness of hearing in the same 

 way as the ears of different people do ? 



What to use. A class of students ; a watch with a reasonably loud tick ; a tape measure. 



What to do. Blindfold each person in turn. Bring watch slowly toward the right ear until the 

 subject can just begin to hear it ; measure the distance. Repeat for the left side. 



Record. Distance in inches at which right ear detected tick ; left ear 



Make a table showing, by the distance in inches at which the tick was heard, the relative acuteness 

 of hearing of each subject for the right ear and for the left ear, and the difference between the two. 



1 . What is the average difference between the two ears ? 



2. What is the range of variation between the best and the poorest right ear ? 



3. What is the range of variation between the best and the poorest left ear ? 



4. What is the average distance for the right ear ? 



5 . What is the average distance for the left ear ? 



6. Why is the difference between the averages less than the average difference ? 



Questions. 1. In what other respects besides acuteness do people's hearing sensations differ? 



2. What practical use can be made in school of the fact that some hear so much more easily 

 than others ? 



3. What practical use can be made of this fact outside of school ? 



4. What is meant by the statement " If there were no ears, there would be no sound " ? 



[102] 



