# How to design a variable slope highpass filter

I want to design some specific slope highpass filter to enhance speech; just like $1$ dB/octave, $2$ dB/octave and more. Is there a method to calculate the coefficients by specific slope?

• uhm, you want that slope specification to be continuous? – robert bristow-johnson Apr 5 '16 at 3:07
• probably check out what a shelving filter is. google "Audio EQ Cookbook". – robert bristow-johnson Apr 5 '16 at 3:08
• In other words: do you want a piece-wise linear enhancement in the frequency domain? For instance flat in the low-frequency part, and $+x$ dB above one specfic frequency? – Laurent Duval Apr 5 '16 at 5:36
• Thanks for everyone.Actually,what I want is just like the respone in this website.support.biamp.com/Tesira/Programming/AEC_in_Tesira (Pre-Emphasis Filter) But,I want to design a program to calculate more slope to use in deffient implementation. Further more,I am try to use fft to implement. – RongJun Huang Apr 6 '16 at 2:33
• Here's a related question (if you swap poles and zeros) I want to link here because it is so difficult to find otherwise: IIR filters with variable roll-off – Olli Niemitalo May 18 '17 at 19:00