Cynthia R. Newman Washington Elementary
3611 E. 114th St.
Chicago IL 60617


After this lesson, the student should be able to

1. relate the pitch of sound to the length of a vibrating object.

2. define words (pitch, source, medium, detector, air conduction, and
bone conduction).

3. examine hearing acuity using the tuning fork by means of air
conduction and bone conduction.

4. discuss how Europe contributed to earlier conventions.

Strategies and Activities:

Activity 1: the session will begin by having the instructor define
vocabulary words.

Materials Needed:

rulers, straws, and glass bottles

Activity 2: (a) increase the length of ruler/straw (vibrating object) to
get a lower pitch.
(b) decrease the length of ruler/straw (vibrating object) to
get a higher pitch.
(c) record the observation made.

Activity 3: (a) fill one bottle with water almost to the top and fill
another bottle half full.
(b) blow across each bottle and listen to he highness/lowness
of pitch of each bottle.
(c) tap each bottle and listen to the highness/lowness of pitch
of each bottle.
(d) record the observations made.

Activity 4: (a) each group will take eight pop bottles.
(b) each group will fill the bottles with the appropriate
amount of water needed to produce an octave.
(c) each group will produce the piano scale by blowing across
the bottles.
(d) record the observations made.

Performance Assessment:

Why was the pitch lower for the bottle with less water when you blew across the
top of the bottle? Why was the pitch higher when you tapped the bottle with
less water?

3 Answer provided clear explanation
Applied principles learned in class
Used previous example in class to support answer
2 Explanation was somewhat unclear
1 Little or no explanation
0 No attempt made to answer questions


If the vibrating column is shorter, the pitch will be higher and vice versa.

Materials Needed:

tuning forks, stop watches, and rubber sticks

Activity 5: (1) students will compare time in seconds for air conduction
and bone conduction to examine hearing acuity using the
tuning fork.
(2) they will work in groups of four (examiner, timer,
recorder and subject).
(3) the examiner will tap a tuning fork with a rubber stick.
(4) then, the examiner will place the tuning fork on the bone
protruding behind the right ear (mastoid process) for 3
trials on the subject.
(5) simultaneously, the timer will time how long any sound was
heard (even the faintest sound that was heard using the
tuning fork) during each trial.
(the timer will start the stopwatch as soon as the tuning
fork is tapped).
(6) the recorder will record the time in seconds.
(7) the subject will hold his/her hand up as long as he/she
hears the sound.
(8) afterwards, the examiner will follow the same procedure
for the left ear.
(9) next, the examiner will place the tuning fork at the
midline of the forehead above the level of the eyebrow for
3 trials on the subject.


The time that the sound was heard occurred longer for air conduction than bone
conduction. Greater energy was required for sound to travel for bone conduction
than air conduction.
Return to Physics Index