Petra,
The sound you are describing is not what I would consider an “ear tone”, which is (I thought) a sound fairly short in duration (under a minute, usually just a few seconds), fairly refined and (fairly high) in pitch. Like Chris, I’ve never knowingly heard the same thing at the same time as someone else. But this sound is commonplace and delicate, so most people take it for granted, I guess.

The humming that I hear (have always heard, and assumed everyone heard) I would describe pretty much as was described in the Taos Hum article, except that I have never been disturbed by it, and to the contrary, always have found it relaxing. Using computer tone-generator software, I can get a similar sound only by mixing in frequencies below 20 Hz (another reason I wondered at their failure to measure that frequency of EM radiation).

The sound you describe seems to be primarily low frequencies, but I am not sure what you mean by “I've only heard it once” – did you mean just the trailing part of the Nisqually sound, or the whole sound? Are the ear tones you normally hear low in pitch?

I have never heard the kind of sound you describe, which seems similar to Charlotte King’s experience.

In the past few months I had noticed the humming sound was louder than usual, even outdoors, and since I had always associated increased volume with fatigue, I wondered to myself if I was not getting enough rest. I did not make a connection with increasing ULF activity in the same time period, but thanks to your influence, I am now thinking about that. (However, I can only measure extreme levels, and as these occurrences became frequent, I can only speculate that the over-all daily ULF levels were higher than normal).

I suppose it is possible that the hum is a natural internal phenomenon that is modulated in various ways, including amplitude, by ULF radiation.

But even when there are extreme levels of ULF, I do not notice any special hearing sensation.

Article posted by Don on infrasound:
I would suppose that ULF sound would accompany ULF EM radiation, because a physical vibration is presumably producing the EM waves, and this physical vibration would simultaneously produce sound waves. But I do not think sound waves can be transmitted so easily as suggested in the article. Even in the case of ULF EM waves, the transmission is (according to educated consensus guess) limited to 30 or 40 km. Also, I cannot conceive how weak ULF sound waves would affect the body, but it is easy to conceive how weak EM radiation of particular characteristics could.

Do you know of PN Nair? This article will probably be of interest.

http://www.rediff.com/news/2001/feb/02spec.htm

Ara