Experiment 5: Introduction to Sound

Objective: The purpose of this lab is to learn the properties of Sound waves. Students will use LabPro and microphone to make four different recordings. These include two "AAAA" Sound from two different people, one tuning fork sound from striking on a soft object, and one soft tuning fork sound. Student will obtain four graphs and analyze the graphs based on the questions provided in the lab manual.

 Figure 1: The sound wave made by a student with an "AAA" sound.

1. "AAA" Sound
a. This  is a periodic wave. From the graph, students can observe the wave has repeating pattern. When students fit the graph to sine function, they can find the wavelength, frequency, and amplitude.
b. About 2 waves are shown in the sample. One complete wave is from one high peak to the second high peak. In the graph there are three peaks, so there are two waves.
c. The probe collected data as fast as the frames separated on TV.
d. There are two waves in 0.02s. The period of these waves should be 0.01s/wave.
e. The frequency should be 1/T=1/0.01=100Hz
f. lambda=v/f=340/100=3.4m. This can be the length of a table in the classroom.
g. w=2pi*f=2*3.14*100=628rad/s
     A=v/w=340/628=0.541m
h. The number of waves would change and be increased. The time it takes to collect the data will increase too. Period, frequency, wavelength, and amplitude wont change.


 
   Figure 1: The sound wave made by the second student with an "AAA" sound.


2.  There are two waves. The period of these waves is 0.009. Frequency is 111.1Hz. Wavelength is v/f=3.06m. The amplitude of waves for this person is shorter. It is v/w=0.487m.



Figure 3: The sound wave made from a tuning fork by striking it on a soft object.

3. The waves from tuning fork is a sinusoidal wave. There are more waves with less variation. The period is smaller, it is 0.0025 s/wave. The frequency is 400 Hz. The wavelength is 0.85m/s. The amplitude is 0.135.


  



 Figure 4: The soft tuning fork sound.


4. The student hit the tuning fork softer and put the microphone away from the tuning fork. The amplitude is shorter. All others stay the same.