Sine Wave 3 - Harmonics and Audio Signals

Make sure the computer speakers are on. The signal being feed to the speakers is a sine wave that completes one cycle or period in 0.01 seconds as shown in the above diagram. One hundred of these cycles would be completed in one second. In the audio world this would be referred to as a signal with a frequency of 100 Hertz.

Press the following buttons to see what affect different frequencies have on the sound

These sounds are not much like a musical instrument. This is because musical instruments like guitars actually make lots of sounds when one of its strings is struck. The way the string is mounted in the guitar means that its motion is actually quite complex. Indeed, it is this complexity that helps us to identify the sound of a guitar when we hear it.

In 1822 Frenchman J.B. Fourier showed that any sound could be re-created by adding sine waves together. Press to find out what happens when you add a 100 Hertz sine wave to a 300 Hertz sine wave.

Press to find out what happens when you add a 100 Hertz sine wave, a 300 Hertz sine wave and a 500 Hertz sine wave together.

To explore the idea of making up sounds by adding sine waves together further, this web page and run the Dotric Sinewaves program. To run the Dotric Sinewaves program now click here and press the Run button in the dialog that appears. See your system administrator if this functionality is blocked on your computer.

To find out more about the Dotric SineWaves program click here.

If you are really interested, you might like to download the DotricDJ program, capture some real life sounds (like a guitar) and look at the waveforms that you get. To find out more about the DotricDJ program click here.

Now that you know all about sine waves proceed to Sine Wave Tutorial 4 to find out about Lissajous figures.