My favorite is still, with `sox` installed, some variation on play -q -n -c1 synth whitenoise lowpass -1 400 lowpass -1 300 lowpass -1 200 lowpass -1 100 gain

My favorite is still, with `sox` installed, some variation on play -q -n -c1 synth whitenoise lowpass -1 400 lowpass -1 300 lowpass -1 200 lowpass -1 100 gain +10 and tweaking the number of `lowpass` filters and their values appropriately