Now that you have an understanding of sound, let’s discuss the ways that we represent sound waves. This picture is a representation of a sound wave.
It’s easier to understand sound when it’s displayed in a nice organized graph like this. And anyone who is interested in sound will encounter these graphs incessantly. So, let’s go over the parts of the graph:
The wiggly line in the middle represents the wave. The X-axis is Time, and the Y-axis is Amplitude. We can observe a few things about our sound from this graph, such as the frequency of the wave. The frequency, which is measured in hertz, is the number of times a wave occurs in a second. If our X-axis in this graph is 1 second, then we can observe that the wave occurs twice in that 1 second. It’s important to note that one cycle is measured from peak to peak, or valley to valley, or every two 0-crossings. Since this wave cycles twice in a second, it is a 2hz wave. Humans can only hear sounds approximately between 20hz and 20khz, so this 2hz wave is too low for us to hear.
We can also observe the amplitude of the wave from this graph. The amplitude of a wave is perceived as the loudness of a sound. So, the higher the mountains are on the Y-axis the louder the sound is.
For another example, lets imagine you come across a similar graph where the wave occurs 20 times in 2 seconds, and the mountains of the wave are smaller. This wave would be 10 hz (since a hz is how many cycles in 1 second, and since this graph is 2 seconds long, we divide the 20 cycles in half), and this wave would be quieter than the graph pictured above.
You will see graphs like this constantly when dealing with audio and sound. There’s one other graph for us to explore that’s called a frequency analyzer, which will we will explore in another post.
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