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2. Catching the Pitch Wednesday March 28 th, 2012 Warm-up: ** Answer in complete sentences below your paste-in*** 1. How is sound transferred as energy? Objective: Students will be able to examine changes in vibrations in order to describe the relationship between pitch and vibration. HW: Wave Interactions HW #2 (Due BY Friday) PD 4: Bring Glue tomorrow for HW assignment Warm-up Answer: --Sound is transferred as energy when a medium vibrates. --Compressions and rarefactions are made due to the vibration. --This makes molecules in the medium hit other molecules. --This transfers energy.

3. Classwork Pitch is one of the most basic tools in a musicians tool box. A musician must have total control over the pitch of any sound they produce. The simplest way to define pitch is by describing it using the terms high and low. Pronouncing the word high in a high voice and low in a low voice will help you to understand the difference between high pitch and low pitch. Did you notice the difference in the sounds? The proper description of pitch is that the sound that you hear depends on the frequency of the sound wave.

4. Making a Stroboe a. Flatten one end of the straw. Cut the end to form a point. See figure 1. Figure 1 end of straw to be cutcut end of straw side view of cut end b. Measure the length of the straw and record your results in Chart 1, Sounds of a Straw. c. Place the cut end of the straw between your lips. d. Exhale through the straw until you produce a sound. Note: you may have to vary the pressure of your lips and the air pressure to make a sound. e. Record the sound you made in Chart 1, Sounds of a Straw. f. Cut the straw in half and repeat steps b - e. g. Cut the straw in half again and repeat steps b - e.

5. CHART 1 SOUNDS OF STROBOE STRAW LENGTH DESCRIPTION OF SOUND Short High Pitch Medium Medium Pitch Long Low Pitch

6. Conclusion 1. Based upon your knowledge of waves describe the relationship between the sounds produced by the stroboe and the length of the instrument. As the length of the stroboe decreased, the pitch of the sound __________.

7. Conclusion 2. Identify the relationship you observe between the rate of vibration and pitch? As the rate of vibration increases, the pitch ___________.

8. Exit Ticket Figure 4 The harp in Figure 4 is an instrument which can produce sounds with many different pitches. Explain the difference in the sound caused by string A as compared to string B using information from the investigation. Be sure to discuss string length, pitch, and vibrations. A B A B