In this section, we will find out how to make sound louder, and voices higher. This is the technical section dealing with waves, but I promise you that at the end of this section, you will be able to use your equalizer and home stereo! As always, we will have a person who will help us understand these concepts better. Today we have Roy McManur.
"Hi Wizard, you may have seen me in such web pages as Science Rules, How to Make a Titration, and Today We Use HTML, Tomorrow Java."
"Amm yah . Well, I was wondering if you could help us understand what waves are, and how they can help us use our stereos."
"No problem. As you know, sound is a wave. If we take a look at our typical transverse wave, the ones we are most familiar with, you will notice some key elements. Before I go on, I think its best if we look at sound as a transverse wave because it is a lot easier to see. We'll save the tough visualization up to you when you get to university. A wave has an up part, called a crest, and a down part called a trough. When a wave passes through a medium, these crests and troughs oscillate, going up and down. The distance between the beginning of a crest and the ending of a trough (or vice-versa) is called a wavelength. Typically, for sound, the wave lengths tend to be very small - smaller than the typical cm.
You may have heard that light too is a wave. Well, if you didn't, then this is a surprise! Light's wave length is so small, that we can only measure it with very precise and expensive equipment. On the other hand, we know that water surfing waves are big enough to hold a surfer. Well if you've surfed, you also know that waves can be very tall, or very shallow. We refer to the height of a wave from a 'rest' or equilibrium point as amplitude. Now if you have higher water waves, you know that you can surf higher - the higher more powerful waves have more energy. Now in sound this means that you'll have a louder sound. The larger the amplitude, the louder the sound, and the smaller the amplitude, the lower the sound is."
"Well that is very interesting Mr. McManur, but I still don't know how to operate my stereo."
"Ah ha, well I'll teach you some more. If you've looked at your stereo, you've probably noticed that 'frequency' (f) is written on it somewhere. Frequency means the number of waves that can pass by a point in one second. Perhaps you have seen this on your equalizer. The equalizer filters certain frequencies that irritate our hearing. I've told you what frequency is, now let me tell you about what that high speed dubbing button does. You have noticed that when you record on high speed, the voices become very fast, and you have something that sounds like a chipmunk. The faster sound is created by an increased frequency of sound, the more of the sound from the tape is being passed to the air in a second - a higher frequency. Likewise, when your walkman runs out of batteries, the sound becomes very slow - because the tape is playing at a lower frequency. Well, there is a lot more to learn about stereos, but you can find out more from Williy the Wizard"
"Thanks Roy, and pleasedon't call me Willy. I told you I am the 'Wizard' now. Hey and thanks for not commenting on my hat."
"Oh yah. Hey Willy, your hat is no good. What are you trying to do? Hide Marge Simpson's hair in there?"
"Yes I am. Thank you.....mmmmm."
Well we have learned a lot about waves and sound thanks to my very intelligent, yet fiendish friends. In the last part of our journey, we will learn a bit about some applications of sound and waves. If you've been following through the pages, you know what to do next.
Waves have properties, and so too sound
Waves have amplitude (volume) frequency (pitch), wavelength (speed), etc.
Applications of waves