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A 1973 report mentions a university study of fifty cases of people complaining about a "low throbbing background noise" that others were unable to hear. The sound, always peaking between 30 and 40 Hz, was found to only be heard during cool weather with a light breeze, and often early in the morning. These noises were often confined to a 10-kilometre (6.2 mi) wide area.
[2]
A study into the Taos Hum in the early 1990s indicated that at least two percent could hear it; each hearer at a different frequency between 32 Hz and 80 Hz, modulated from 0.5 to 2 Hz.
[3]Similar results have been found in an earlier British study.
[4] It seems to be possible for hearers to move away from it, with one hearer of the Taos Hum reporting its range was 30 miles (48 km).
[5]There are approximately equal percentages of male and female hearers.
[3][6] Age does appear to be a factor, with middle aged people being more likely to hear it.
[7]:43
In 2006, Tom Moir, then of
Massey University in
Auckland,
New Zealand, believed he has made several recordings of the Auckland Hum.
[8][9] His previous research using simulated sounds had indicated that the hum was around 56 hertz.
[10