While messing around in MMA, I was trying to draw shapes in `Spectrogram`s of `Audio@Table[__]`s and I discovered that you can make a curve appear in the spectrogram with `Sin[F[t]]` where `F[t] := Integrate[f[x],{x,0,t}]` and `f` is the function of the curve you want to appear in the spectrogram, from time to frequency. And if you want to color in a region in the spectrogram, you add the curves a la `Audio@Sum[Table[__],_]`. To get something like white / brown / etc noise you add up a bunch of your function with a random sample of some distribution for a parameter, eg: `fa t + f (-fa + fb) t` linearly interpolates between `fa` and `fb`, and the parameter `f` is the interpolating parameter. If you insert a random uniform on `[0, 1]` in for `f`, then you fill in the region from `[fa, fb]` in your spectrogram