This is the goal transfer function (x is frequency in Hz): return pow(10, (x <= 250 ? 1 : 1 + 1.5*log2(x/250) + (x > 5000 ? 5*log2(x/5000) : 0)) / -20); T

This is the goal transfer function (x is frequency in Hz): return pow(10, (x <= 250 ? 1 : 1 + 1.5*log2(x/250) + (x > 5000 ? 5*log2(x/5000) : 0)) / -20); This is the header library that generated the filter to match this as closely as possible: https://gist.github.com/LnxPrgr3/8262666 https://gist.github.com/LnxPrgr3/8262666 Then, it's time-reversed and the sign flipped, and an impulse is added at sample 0. This filter translates to mid/side stereo, applies this kernel to the side channel, then converts back to L/R for playback.