Audio EQ: What Is A High-Pass Filter & How Do HPFs Work? – My New Microphone
Why do the orders of hi/low pass filters go in 6 dB increments? - Sound Design Stack Exchange
Frequency Response by AC Analysis on One-Pole Low Pass Filter for the Modification of Fixed Physically Constraints and to Manipulate Sound into a Different One :: Science Publishing Group
Second Order Filters | Second Order Low Pass Filter
Filter
What's the 3dB cutoff frequency in a low-pass filter? - Quora