Figure 2.6. This is a frequency response graph. The horizontal axis is labeled Frequency in hertz. The scale is from 1 to 1 M which stands for 1 million. The distance between 1 and 10 is one sixth of the entire horizontal graph. The distance between 10 and 100 is also one sixth of the horizontal. Each decade covers one sixth of the horizontal distance. There are intermediate marks between 1 and 10 that are approximately one third of the distance between 1 and 10. These marks are at 2 and 5. There are similar intermediate marks at 20 and 50, also at 200 and 500 and so on. The vertical axis is labeled attenuation in dB. It is linear. The top of the scale is 10, the next line down is zero, the next minus 10, next at minus 20, and so on down to the bottom line which is minus 60. The distance between zero and minus 10 is the same as that between minus 10 and minus 20 and is the same as between minus 20 and minus 30 and so on. Now for the data curve. At 1 hertz the value is zero dB. It continues flat to the right and is still zero at 200 hertz. Just after 200 hertz it begins to fall away from zero. At 500 hertz it appears to be at about minus 1 and at 1000 hertz it is at minus 3 dB. At 2000 hertz it is at about minus 6 and at 5000 hertz it is at about minus 14. Somewhere between 2000 and 5000 hertz the data curve becomes a straight line sloping down to the right. At 10000 hertz it is at minus 20 dB, at 100000 hertz it is at minus 40, and at one million it is at minus 60 dB. End verbal description.
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