Lesson 1:

The purpose of this exercise is to provide very basic manipulations of a sine or cosine wave.

Figure 1 is a sine wave with amplitude of 1 and a frequency of 10 Hz.

1. Please click on the Java applet.
2. Enter the values of the amplitude and frequency.
3. Make sure the "wave form" is chosen as Sine and power to be 1. Press the "CLEAR" button, then press the "+" button to see the sine wave.
4. Press the "listen button" to heard the sound.

You should have the following picture in your JAVA applet's graph window.

Fig 1

We can change the amplitude to see another sine wave.

1. In your JAVA applet, leave everything to be the same but change the amplitude value to 5.
2. Press the "CLEAR" button, then the "+" button.
3. Press the "listen" button to hear the sine wave.

The following wave form should be display on the JAVA applet.

Fig 2

As you can see, changing the amplitude only makes the Y component large. The frequency and the period did not change for the sine wave. You may say that amplitude determines the loudness of the sine wave by its audio output.

After looking at the amplitude of a sine wave, let us turn our attention to the frequency of the sine wave. Figure 3 is the same as figure 2 but at a higher frequency.

Fig 2.

Compared to figure 2, there are more cycles per period in figure 3. The frequency determines the number of cycles per time in a wave. You may say how fast or slow the sine is moving. From the audio outputs of figure 2 and figure 3, figure 3 has a slightly higher pitch then figure 2. If one changes the sine wave at a higher frequency, you may hear sounds that sound like a chipmunk. You can give it at a try at a higher frequency if you like. Just change the frequency in the frequency box of the JAVA applet and redraw it. Please note that changing to a higher frequency will take a longer time for the output of the graph. Please click below to return to the table of contents when you are ready for the next lesson.

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