|| home ||| units ||||| help

Trial 2 - Explore Loudness and Pitch

1. Start up the Sound Grapher.

   
2. Hum into the microphone. Try changing how loudly you hum. How does the graph change to show you how loud the sound is?
   
   
3. Make a tube by rolling up a piece of paper. Put one end of the roll by the microphone and hum into the other end. Does this make the sound louder in the Sound Grapher? Why do you think this happens?

   

   
   
   
4. Make the same sound close to the microphone, then farther away. What changes in the Sound Grapher? Does the loudness decrease? Why do you think this happens?
   
   
   
5. Here are two sounds. The first is lower in pitch and the second is higher in pitch. Play the two sounds and observe them in the Sound Grapher. Take a snapshot of each one.
   
   
6. Find the repeating pattern in each snapshot. Count how many times the pattern repeats on the screen.

   Number of times the pattern repeats:

   Lower pitched sound:

   

   Higher pitched sound:

   
   

The Sound Grapher is a picture of the sound frozen in time. The pattern for the higher-pitched sound is closer together and happens faster. This is what 'pitch' means. It is a measure of how fast the sound vibrations are happening.

Another word for how fast the sound vibrations are happening is 'frequency'. For higher-pitched sounds, the vibrations happen faster or more frequently, so they have a higher frequency.

7. Now hum into the microphone and try to change the pitch. As the pitch goes up, the repeating pattern should get closer together.
   
   
8. Take a snapshot of a low-pitched hum. Take another snapshot of a high-pitched hum. Find the repeating pattern in each snapshot. Draw a picture of the repeating pattern.
   

   Lower pitch

   

   Higher pitch

   
   
9. Count how many times the pattern repeats on the screen.

   Number of times the pattern repeats:

   

   Lower pitched sound:

   

   Higher pitched sound:

   
   
10. Your data appears below. How does the number of times a pattern repeats affect a sound's pitch?

    Pitch	Picture	How many repeats
    Lower
    Higher

    
    
11. Have one person make a uuuu sound and another person whistle. If you can't whistle, find someone in the class who can. Which sound has the higher pitch? How can you tell?
    
    
12. Make both sounds at once into the Sound Grapher. Take a snapshot of the combined sounds. Can you see the patterns for both sounds at once in the Sound Grapher?
    
    
    
13. Draw the pattern.
    
    
14. What part of the pattern is the whistle? What part of the pattern is the uuuu sound?