I didn't suggest 20 bits; I suggested 20 distinguishable degrees of discomfort. Medical diagnosis sometimes uses ten, or is that six? which I thought was wrong at the low end — a dust speck is much less discomfort than anyone goes to the doctor for. 4 to 6 bits could encode 16 to 64 degrees of discomfort. I did presume that discomfort is logarithmic (since other senses are), and I conflated pain with irritation, which are not really subjectively the same.