Waves

Sound can travel through liquids and solid objects, but for this explanation we will focus on how it moves through air. Sound travels through the air in waves of compression. These waves increase and decrease the air pressure as they travel. The picture to the right will help exemplify the following information. Each sound has a certain pitch, that is, how high or low the sound is. A sound’s pitch is determined by its frequency. We measure that in hertz. Hertz are the number of complete wave cycles per second. A 100 Hz tone completes 100 wave cycles per second to produce that note. We measure loudness, also known as amplitude, in decibels. This is how high or low the pressure of the wave is from the ambient pressure of the air it passes through. As the picture suggests, a louder noise has much higher amplitude than a softer sound with lower amplitude.

Decibels

For reference, I’ve included a decibel chart to the left so you can better understand how the system works. It is not a linear scale; it is what we call a logarithmic scale. Numerically, a 110db sound appears to be only 10% louder than a 100db sound but this is not the case! For every 10db added we perceive the sound to be twice as loud. This means that the 110db sound is 200% louder than the 100db sound! On the next page we will talk about how a speaker produces the sounds we hear.

Next>>Speakers Explained

Content Written By Steven Solazzo