"Hum" rating scale, as per L. Grant

0 - no sense of hum at any time, ever, period.

1 - barely hear it, not sure, but can't say nohow, nowhere, notime.

2 - definetly hearing it, in background, has to be quiet and probably
    mostly heard in bed.

3 - Beginning to be a nuisance at times, heard much of the time and can
    hear when mobile as opposed to lying down. Not that awfully bad and no
    physiological symptoms noticeable.

4 - heard most or all of time, strong solid signal, perhaps a faint sense
    of rumbling with it, getting tired of hearing it, it disrupts thought
    when studying or doing anything quiet, still no physical symptoms
    however.

5 - This is getting pretty dicey.  It's there, its loud, I feel a bit
    tired part or all of the day it distracts me and I think I'm getting a
    headache, no, I know I'm getting a headache. This is a drag, I can't
    concentrate, really wish this thing would shut off

6 - Ow! It's very loud, I can barely think. it knocks me into a chair and
    I can barely get up, my head hurts, I've got muscle spasms, twitches,
    aching joints and muscles. Turn this off!

7 - The room is shaking, vision is blurred, heavy physiological symptoms,
    exhaustion, starting to get very tense and really agitated. Strong
    sensation of rumbling and vibration.

8 - All of the above plus a powerful sensation of electrical shocks going
     through the body all there is is hum and trying to survive it.
9 - one notch for future expansion.

I - Increasing
U - Unchanged
D - Decreasing

Example: 4INM = level 4, increasing, New Mexico