> Sound.SC3.UGen.Help.viewSC3Help "BLowPass"
> Sound.SC3.UGen.DB.ugenSummary "BLowPass"
> :t bLowPassCoef

> import Sound.SC3.ID

> let { i = soundIn (mce2 0 1)
>     ; f = mouseX KR 10 20000 Exponential 0.2
>     ; rq = mouseY KR 0 1 Linear 0.2 }
> in audition (out 0 (bLowPass i f rq))

> let { i = mix (saw AR (mce [0.99, 1, 1.01] * 440) * 0.3)
>     ; f = mouseX KR 100 20000 Exponential 0.2
>     ; rq = mouseY KR 0.1 1 Linear 0.2 }
> in audition (out 0 (bLowPass i f rq))

Calculate coefficients and use sos.
> let { i = mix (saw AR (mce [0.99, 1, 1.01] * 440) * 0.3)
>     ; f = mouseX KR 100 20000 Exponential 0.2
>     ; rq = mouseY KR 0.1 1 Linear 0.2
>     ; (a0, a1, a2, b1, b2) = bLowPassCoef sampleRate f rq
>     ; flt ip = sos ip a0 a1 a2 b1 b2 }
> in audition (out 0 (flt (flt i)))