Figure 5.2. This is a graph in which the vertical is marked off in 3 dB intervals from 12 dB at the bottom to 54 dB at the top. There's no mistake. All values on the vertical axis are positive. At 10 Hz the 5 curves have the following values. 15.5, 26.5, 34, 40.5, and 49 dB. At 100 kHz all 5 have these values. Off the low end of the scale, 21, 30, 38, and 51.5 dB. The tone flat line starts out at 34 dB. But by 200 Hz it has fallen by a noticeable amount. At 500 Hz among a tangle of colored lines it appears to cross the 33 dB scale line. It continues to fall until at 20 Khz it has fallen to the 30 dB scale line. This is one of the flaws mentioned in the figure caption. The boost and cut lines converge toward the tone flat line and all come together at 640 Hz. But instead of staying together they cross with the green and blue lines coming out above the flat line and the light blue and purple lines below. This is the second flaw mentioned in the figure caption. They spread out to a maximum of 3 dB at 850 Hz. Then they come back together at 1200 Hz. They all cross and come out with the green and blue lines below the red tone flat line and the light blue and purple lines above. As the frequency continues to increase the lines spread farther apart and achieve their end values at 100 kHz. End verbal description.
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