filter - slope
The slope of the attenuation varies with the design of the filter. Simple filters with one resistor and capacitor (RC) will have slopes of 6 dB/octave, which means that for each doubling of frequency, the attenuation increases by 6 dB.
Each pair of RC elements is called a pole and the slope increases as the number of poles increases. A two pole filter will have an attenuation of 12 dB/octave, whilst a four-pole filter will have 24 dB/octave.
