UPDATE: The 91 dB reading was actually dBC, not dBA. This is significantly worse. As YouKnowWhoTheFuckIAM pointed out, locatability is a factor in the health effects, and high pitched frequencies are bad in this regard. As there are likely sub-sonic sounds which would not appear in the dBC reading, the volume is even higher, this would push the noise inside the facility to sonic weapon territory, and ear protection can't cover the full spectrum that well, it's either or. Persistence of the sound is the worst it could possibly be: 24/7. One doctor said he sees one patient a week with symptoms from this. From one rural settlement. Everybody's fucked
There are two types of disabilities caused by excessive noise: those that have a neurological or psychological cause (whose impact is measured in dBa) like tinnitus or cardiovascular issues stemming from anxiety, and those that are directly from trauma to the ear (measured in dB). dBa is corrected for the frequency response of the human ear, while dB is a more objective measure of pressure level.
The recent Time article featured a former oath keepers member with a measuring device (most likely dBa, he got 91) on the opposite side of the road of a bitcoin mine situated right next to residences. I traced the buildings on OpenStreetMap and calculated the noise level in the area. In the previous post there was someone that said the sound attenuates quickly. This is only true for point sources at large distances (inverse square law). I wrote the following python code that I think is more appropriate for this situation[1]:
G = 50
v = 331 # speed of sound
l = 10 ** (91 / 20)
def D(R):
return exp(G/(R * v ** 2))
def d(t1, t2):
x = abs((t1[0] - t2[0]) ** 2 + (t1[1] - t2[1]) ** 2)
return x * D(x) ** 2
def pair(emitter, target):
return l / d(emitter, target)
I found the noise within the facility to be 118 dBa. Assuming that the audio recording in the article has a flat frequency response (TV is really EQ'd so this can be false), this is 131 dB. At that level ear drums rupture within seconds. The workers are lucky that the noise peaks at frequencies that can be blocked by ear protection.
Outside the facility, levels ranged from 66 to 95
Noise levels of 50 dB(A) or greater at night may increase the risk of myocardial infarction by chronically elevating cortisol production
Approximately 35% to 40% of office workers find noise levels from 55 to 60 dB(A) extremely irritating. The noise standard in Germany for mentally stressful tasks is set at 55 dB(A), however, if the noise source is continuous, the threshold level for tolerability among office workers is lower than 55 dB(A).
Physicists reading this are welcome to point out what i got wrong :)
[1] https://medium.com/timematters/universal-inverse-square-laws-without-singularities-d25c47ef8d77
Quibble: dB is not an objective measure, nor does it purport to be. It uses an objective yardstick (pressure) but it is scaled for hearing according to an approximation of subjective experiences (hearing) of pressure.
I’d also strongly suggest that not only “can” the frequency response measured off the TV be false, it will be false. It’s not just that TV sound has been highly processed, there’s just no way that the audio equipment a news crew uses picks up anything like the true sound of an environment, especially not the sort of full-spectrum noise emitted by an industrial compound. Of most interest here is that the signal picked up by those mics is liable to drop off somewhere below the range of human speech, whereas industrial equipment like that is liable to have big peaks beneath those frequencies and further, descending well past 20Hz (the bottom end of human hearing).
Persistent low frequency and sub-sonic noise is associated with severe mental distress and physical ailments.
In fact this is why it’s important to recognise the subjectivity of the decibels measure: (not only because) the body/brain responds differentially to frequencies across the spectrum, and at different volumes. It also responds according to all sorts of other variables, and these can’t really be untied from the question of noise level. Persistence, locatibility, perceived subjective control of one’s own aural environment - all of these are fundamentally tied to both the “physical” and “psychological” effects of hearing (insofar as these can be untied).
Some of the symptoms described in the article (nausea, vertigo, fainting, panic attacks) can be the result of all of these variables, given a sufficiently persistent uncontrollable sound source. You just can’t untie them and peg them all to objective noise level.
Others (such as hearing loss and fluid leaking out your ears) are associated with prolonged exposure to sub-sonic noise, and again this can be as much an issue of time and persistence as “objective” sound level.
If we want to know “how bad” a noisy environment is for people, we simply don’t have a choice but to look at its effects first. You just have to look at the subjective effects people experience first, or you’re not looking at sound in the first place. You’re grasping at some independent objective measure which won’t ever actually tell you what you want to know, except in the most limited circumstances.