To be clear, I do understand how sound works

Replying to a criticism of my last post

This post is kind of inside baseball for the ongoing drama around my last post on Benn Jordan’s infrasound videos. It might not be interesting to regular readers, but if you’d like to see me use my physics background to defend my good name, read on.

After failing to respond to any of the ways I had pointed out in my last post that he was misrepresenting every study he flashed on the screen, Benn Jordan shared a blog post someone else had written called Andy Masley doesn’t understand how sound works. The conclusion of the post is that I don’t actually understand the science of sound, my criticism falls apart, and I’ve become ideologically motivated to defend data centers over seeking the truth.

However, the criticisms are all wrong, confused, and seem to be coming from someone who’s lurching to assume I have bad motives. And Jordan obviously knows that it’s all mistaken, because he works on and thinks about sound way more than me, and I can run circles around it. I’m going to use this post to respond to them individually. Jordan obviously knows they’re wrong, because he works with sound a lot, and is once again tricking his audience.

I wasn’t originally going to respond to the blog post, because it’s pretty bad throughout, but since Jordan shared it I do feel compelled to explain why it’s wrong.

Criticism 1: Decibels: intensity vs pressure

The first section is called “He does not seem to know what a decibel is measuring”

Masley claims that “Every 10dB increase represents a 10x increase in sound intensity.” This is technically true, but it is the wrong quantity for the argument he is making. Intensity describes the power per unit area carried by the sound wave through the air. What matters for the biological mechanisms Jordan is describing (pressure on the eardrum, stimulation of vestibular structures, outer hair cell response) is not intensity but pressure. And while a 10dB increase represents a 10× increase in intensity, it represents only a ~3.16× increase in pressure. Reporting the intensity ratio rather than the pressure ratio inflates the apparent safety margin by roughly a factor of 300. By the quantity that actually maps to the effects Jordan is proposing, the gap between residential data center levels and occupational exposure limits is one to two orders of magnitude in pressure, not the five orders of magnitude that Masley’s framing implies. It matters significantly less what the power of sound is at the source here than the pressure change at the point of “impact” for the listener.

You can translate a sound’s decibel level into an intensity ratio or a pressure ratio. They both describe the same physical quantity. If residential data center levels sit roughly 50 dB below occupational exposure limits, that gap is both a ~100,000× intensity ratio and a ~316× pressure ratio. Which one we should look at depends on the situation we’re trying to understand.

It’s true that sound pressure describes the potential for physical harm once the sound reaches your ear. But to understand the amount of energy you need to create that dangerous pressure in the first place, you need to know the intensity.

Intensity matters here because it tells you roughly how much more energy the data center would need to contribute to produce enough sound to be harmful to us. The intensity being 100,000x smaller than it needs to be implies that the data center would need to convert 100,000x as much of the energy flowing through it into sound as it currently does for it to harm us. This is obviously ridiculous!

This is a useful comparison to make to understand how reasonable the situation is. The critic just lurches to assume this doesn’t matter at all:

It matters significantly less what the power of sound is at the source here than the pressure change at the point of “impact” for the listener.

I think for understanding how realistic the chance of a data center harming us with infrasound is, it does in fact help to know that the data center would need to be 100,000x as large to produce adequate levels of infrasound to harm us. The critic assumes that this means I’m acting in bad faith. I disagree! The whole point of my post is to understand whether the source of the sound can produce enough sound to harm us.

Masley conveniently only cited the broad occupational guidance for 8-hour workdays while omitting the exposure limit for workplaces requiring maintained mental concentration, which is a much lower 86dB. OSHA also identifies 85dBA as the occupational limit for sound exposure over an 8-hour period. Using this number for comparison, data centers are only ~4x quieter than occupational standards allow for certain roles.

These figures are for eight hours of exposure. The dose makes the poison. It’s quite absurd to say “this is under the threshold for eight hours of exposure, so it’s surely under the threshold for 24/7 exposure!”

The study notes that the impacts of infrasound may pose greater risk to “pregnant women and adolescents,” possibly justifying an even lower rating of dBG.

I will concede a point here that occupational limits are far above residential limits. However, both remain far above what a data center can produce. The reason I hadn’t gone into detail about this is that as noted in the post itself, these occupational levels (including the advise for pregnant women and adolescents) are from old government advice that traces back to papers that don’t replicate, and that infrasound experts have commented on as not being reliable. I’ve already addressed this criticism, but the author is writing this as if I’m trying to hide it. Again, it’s hard not to read this as a bad faith response hoping that the reader doesn’t actually go through my original post.

Masley handwaves away this last point, but studies have shown that there is a potential link between chronic sound exposure during pregnancy and negative health outcomes. The CDC even tells pregnant women:

Avoid low frequency sounds (noises you feel as a rumble or vibration). Low-frequency noise travels through your body more easily than high-frequency noise. Low-frequency noise can cause changes that could affect your developing baby.

This page never mentions infrasound and only lists volumes of low frequency sound that I’ve agreed could be harmful at infrasonic frequencies. And the harms listed are fetal hearing development, not any of the symptoms Jordan lists. It’s also precautionary and doesn’t cite any evidence. Again, I’m not ignoring anything here.

Criticism 2: Perception thresholds/does infrasound become audible?

The second section is called “He does not understand what a perception threshold is.”

Masley’s central rhetorical move is structurally simple: the perception threshold at 10 Hz is 97 dB; residential infrasound levels are below that; therefore, there is no effect.

This is a non-sequitur.

A perception threshold is the level at which a conscious, reportable sensation occurs. It is the floor below which you cannot perceive something. It is not the level below which biological effects cease. These are different things, and conflating them is not a caution any serious researcher in this field would permit themselves.

The author is correct that these are different. I made that clear in the post itself.

I never once said that “Because infrasound isn’t audible, it can’t affect you.” I’m basing all this on what looks to me like a pretty solid separate scientific consensus that inaudible infrasound doesn’t seem to harm us, so therefore it only becomes harmful when it behaves like normal noise pollution (when we can hear it) or when it’s extremely extremely loud and physically harms us.

My argument isn’t a logical deduction from my blind belief that “you can’t hear it” to “it can’t affect you.” It’s an empirical summary of what the literature on infrasound health effects has found. For about sixty years now, researchers have gone looking for physiological and clinical effects of infrasound at sub-perception levels. Properly blinded exposure studies don’t find them. The studies that claim to find them are generally unblinded, badly controlled, or fail to replicate. The nocebo studies reliably produces the symptoms people attribute to infrasound just by telling subjects that infrasound is present, with no actual infrasound required. That’s the pattern I’m drawing on. “Sub-perception stimuli can in principle have effects” is true in the abstract. When you go looking in this specific place though, you don’t find the effects being claimed.

The author is describing my argument as a logical syllogism and then saying this is a non-sequitur. But this isn’t a syllogism at all, it’s a summary of all the good scientific literature on the problem. If the author (and Jordan) think the literature is wrong, they need to engage with it directly.

In fact, Jordan makes this point, comparing infrasound potentially to ultraviolet light: despite being imperceptible, he argues, these both can cause harm in humans. Masley dismisses this out of whole cloth simply because “this blurs two opposite ends of the audible spectrum.” Because one is infra- and the other is ultra-, it’s apparently not even worth considering the broader point that imperceptible waves can be harmful in some scenarios despite their imperceptibility.

No that’s not what I’m saying. I’m saying that Jordan is suspiciously lurching to the extremely high energy end of the light spectrum when we know that the low energy end (comparable to infrasound) doesn’t have negative impacts on us if we can’t detect its presence.

Maybe all comparisons to light are bad. I was mainly suspicious that Jordan lurched from an invisible harm we obviously know is real (UV damaging us) to infrasound. Maybe this was unfair? Idk.

Here is the extraordinary part. Masley himself cites this directly. He writes: “research suggests that while inner hair cells don’t respond to infrasound, outer hair cells of the cochlea can respond to very low-frequency sound at levels below what we consciously detect, and some studies have reported cochlear or brain responses under near-threshold or below-threshold conditions.” This implies that sub-threshold sound can have an impact on humans.

He then, in the very next sentence, dismisses the implication entirely: “But no one has shown this mechanism produces the long list of real-world symptoms people often blame on environmental infrasound.” He is now using his belief as argument in support of the same belief.

The author has a pattern of accusing me of circular reasoning when we actually just disagree about empirical claims.

• Claim 1: there exists a measurable physiological response to sub-threshold infrasound somewhere in the body.

  • This is true. Outer hair cells respond, as I acknowledge in the post.

• Claim 2: this response produces the specific symptoms Jordan is attributing to data center infrasound. Things like vertigo, heart palpitations, cortisol dysregulation, insomnia, cognitive impairment, and the rest.

  • This is not established at all, and all studies trying to find these symptoms from infrasound have come up with nothing.

Therefore, I conclude that because 2 seems to be wrong, our best bet right now is to assume the outer hair cells that do respond to infrasound don’t have an effect. If they did, why can’t we find it anywhere?

My argument isn’t “ignore the mechanism research.” It’s “the mechanism research does not license the leap from ‘outer hair cells respond’ to ‘residential data center infrasound is making people sick.’ That’s a separate claim that needs its own evidence, and the studies built to test it keep coming up empty.”

I’m not using my conclusion to support my conclusion.

Sub-threshold stimuli produce measurable physiological effects in virtually every sensory system we have studied. This is not controversial.

This sentence is doing a lot of work it hasn’t earned.

Yes, you can find detectable physiological responses to sub-threshold stimuli in lots of sensory systems. The magnitudes of these effects are typically tiny, measured in milliseconds of reaction time or microvolts of neural activity, and detectable only under tightly controlled lab conditions.

The author is using this to imply that sub-threshold infrasound could plausibly cause the symptoms Jordan’s describing. But given the state of the evidence, this is a huge unsupported leap. Making this leap is how you get Wind Turbine Syndrome.

There is a deeper problem here, too. Jordan’s entire argument is about sub-threshold effects. His claim is not “people can hear the data center” or “people can consciously detect the data center.” His claim is “the pressure waves affect biology below the level of conscious perception.” Masley’s rebuttal is “the signal is below the threshold for conscious perception.” Yes, obviously, that is the point.

Masley has spent hours attacking Jordan for claims Jordan never made, because Masley apparently believes “sub-audible” might as well mean “nonexistent.”

Jordan’s first video is literally called What You Can’t Hear Can Hurt You. The whole post is a response to that argument.

My actual claim is that when researchers design experiments to test whether sub-perception infrasound causes the health effects Jordan attributes to it, it doesn’t. That’s a direct response to Jordan. The critic has read “the studies testing Jordan’s claim consistently find no effect” and somehow heard “Jordan isn’t making that claim.” I don’t know what to do with that.

Criticism 3: Confusing “perceptible” with “audible”

The threshold error described above is quantitative: Masley treats the audibility threshold as the floor below which all biological response stops. What I want to flag now is a separate, conceptual error that runs beneath it – one he commits so consistently that I am not sure he realizes he is committing it.

Audibility and perceptibility are not the same thing.

Not only do I realize that, I make it clear in the post!

Throughout Masley’s piece, “inaudible” does the work of “undetectable,” “imperceptible,” and “biologically inert” – three claims that are not equivalent and that require separate evidence. He never makes this distinction. He appears not to know it exists despite citing research which clearly states:

Pure tones become gradually less continuous, the tonal sensation ceases around 20 Hz, and below 10 Hz it is possible to perceive the single cycles of the sound. A sensation of pressure at the eardrums also occurs. The dynamic range of the auditory system decreases with decreasing frequency.

I do make this distinction, I just say they seem to overlap despite being distinct. In my opening part on the science of infrasound, I explain that our experiments seem to find that 1) inaudible infrasound doesn’t have an effect, so 2) the only effects happen when it becomes audible. I also clarify that we can sometimes perceive infrasound as physical pressure on our ears and chest before hearing it, and at that point it becomes dangerous to us.

Consider the vestibular system. The semicircular canals of the inner ear respond to pressure changes and acceleration. They do not produce conscious auditory perception – they produce balance, orientation, and spatial awareness. Low-frequency pressure waves can stimulate vestibular structures at levels far below what the cochlea registers as sound. The sensation, if any, is not heard. It is felt as dizziness, unsteadiness, or nausea. This is not speculative. It is the operating basis of clinical tests like vestibular-evoked myogenic potentials, a standard tool used by ear, nose, and throat doctors.

The study is on very loud stimuli (in the 95-105 dB SPL range) which reliably evoke responses, delivered directly into the ear canal via insert earphones. Below about 75-85 dB SPL you stop getting reliable results, which is why the test uses the levels it does.

Studies have shown a signal can be inaudible and still make you dizzy above the occupationally safe decibel range.

This review doesn’t say what the author is claiming.

The sentence the author seems to be referencing describes "isolated reports" of vestibular symptoms following exposure to wind turbines and rocket engines, phrasing that, in a clinical review, means "case reports exist, no established syndrome." The same paper explicitly states that the phenomenon "is not fully understood" and that "ongoing research continues to study" whether low-level infrasound produces vestibular effects. And the research has since been done, and I cite it throughout my post!

The most telling moment in the piece is one we have already visited. Masley cites Salt & Hullar – a study specifically about a mechanism by which the inner ear detects infrasound without rendering it as conscious sound. The outer hair cells respond; the signal is processed; no auditory percept is generated. This is, precisely, detection without audibility. Masley cites it. Then he just handwaves away the implication because there hasn’t been enough follow-on research on the subject. This would be fine if the headline of his article was “I’m not entirely convinced that infrasound is a problem.” But no, the idea of infrasound being potentially problematic is fake, pseudoscientific, conspiracy theory.

I hand wave it away because it identifies a mechanism that could create an effect, but we’ve tested for that effect over and over and haven’t found it. Anyone claiming that science implies the effect is actually there is in fact doing pseudoscience.

The cash-out is this. Jordan’s entire claim is about perceptible but inaudible effects – pressure waves that the body registers through pathways other than conscious hearing. Masley’s entire rebuttal is that the signal is inaudible. These two writers are not disagreeing about evidence. They are using different definitions of what counts as the phenomenon being studied. And Masley does not appear to realize this, because he appears to believe that “you cannot hear it” and “nothing is happening” are the same sentence despite repeatedly citing studies which state the contrary.

This is so bizarre that I don’t even know how to respond to it. Reading it, I kind of just feel deeply tired. How can you come away from my post and honestly write this?

Criticism 4: Nocebos are unfalsifiable

Masley relies heavily on the work of Crichton & Petrie, a body of research on the nocebo effect: show one group a video emphasizing harm from wind turbine infrasound, show another group a neutral video, expose both to real and sham infrasound. The high-expectancy group reports more symptoms, including during sham exposure. This is a real finding. It belongs in any honest treatment of this research area.

But here is what the Crichton & Petrie studies actually show: high-expectancy groups report more symptoms than low-expectancy groups. They do not show that low-expectancy groups report zero symptoms. They do not show that infrasound has no physical effect at all. They show that expectation modulates symptom reporting.

A study showing that expectation amplifies a signal is not the same as a study showing there is no signal. Masley treats “nocebo effects exist” as synonymous with “nocebo effects mean your research is bunk.” This is not how that works.

This isn’t how I treat the nocebo effect in the post. I very clearly separate studies that try to test for infrasound harms from studies that test for a nocebo effect. I first try to show that studies testing for harms of infrasound below perceptible levels consistently don’t find any, and then talk about how studies show that you can get a pretty decent nocebo effect on infrasound and generate similar symptoms. I don’t say anywhere that the nocebo studies alone prove that infrasound is from the nocebo effect. The nocebo effect would be clearly falsified if people exposed to infrasound who weren’t primed to feel bad had any measurable negative reactions at all. Best I can tell from every serious inquiry that’s looked into this, they don’t. I use the nocebo effect as “this seems very likely to be what’s causing the symptoms once we know they’re not caused by infrasound” rather than “this proves that the symptoms are caused by the nocebo effect.” Again I think this is just a bad faith reading of my post.

Consider what this means for Jordan’s double-blind experiment. Jordan ran a study with a “haunted painting” cover story, specifically to equalize expectation across groups. Masley’s response is to dismiss the entire design by leading with the nocebo literature – in effect assuming a nocebo explanation regardless of what the blinding protocol was. This is unfalsifiable reasoning. If nocebo explains symptoms when the design is bad and nocebo explains symptoms when the design is good, then crying “nocebo effect” is more rhetorical shield than scientific analysis.

I addressed six separate problems with Jordan’s study, only one of them was that he was actively priming each group to feel bad (which does in fact seem relevant!). Again this just flatly misrepresents my post that anyone can read.

Furthermore, Crichton & Petrie show that expectation modulates symptom reporting. They do not show that infrasound has no effect. This is not the “exact opposite” of what Jordan claims. It is, at most, an important qualification to it.

I didn’t use Crichton & Petrie to argue that infrasound has no effect, I used them to say that the nocebo effect seems real, and since I had already used other studies to argue that infrasound has no effect, this looks like the next best explanation.

Criticism 5: The evolutionary argument

Natural infrasound – from thunderstorms, ocean microbaroms, atmospheric gravity waves, wind over terrain – is intermittent, spectrally broad, and non-stationary. It varies by season, geography, weather. It is not a constant feature of any individual’s sensory environment.

Industrial infrasound from a data center HVAC plant is continuous, tonally pure at specific frequencies, and temporally consistent.

It’s correct that natural infrasound is intermittent and broadband while modern industrial infrasound is continuous and concentrated at specific frequencies. But the point about evolution I’m making doesn’t depend on the sounds being identical, just whether human bodies have any reason to have evolved a generalized harm response to inaudible low frequency pressure waves. The biology just doesn’t seem to be there. If we evolved this way, people would mostly not live near the ocean and would be regularly sick if they did. We don’t actually observe any evidence that humans or other animals living near the ocean were evolutionarily selected against. And again, we’re just not getting any evidence that we evolved this way from any of the many good studies done on infrasound.

Arguing that humans must be adapted to industrial continuous-tone infrasound because we evolved alongside transient broadband natural infrasound is like arguing that humans must be adapted to staring at a 500-nit monitor six inches from our faces for twelve hours a day because the sun has always existed.

The sun has always been bright. This does not make a welder’s arc safe to look at without goggles.

The difference is that with these is that we evolved to be able to see the light a monitor gives off, and we evolved to see the light a welder’s arc gives off. We did not evolve to see the infrared light either gives off, but we did evolve to physically feel that infrared light when it gets to be so much that it’s dangerous to us. Similarly, we can detect infrasound when it’s starting to become dangerous to us. Thanks evolution! Have you ever worried about the infrared light your monitor gives off? That seems like the comparable case here, not visible light.

Refrigerators: typically ranging 40-50 dB at around 400-500 Hz (not infrasound!) Washing machines: ... the sound they emit is between 100-1000Hz (again, not infrasound!) Trains: ... these emit sound all over the audible range.

Refrigerators, HVAC systems, washing machines, and most rotating mechanical equipment do produce infrasound alongside their audible sound?

We’re surrounded by mechanical sources producing low-frequency and infrasonic energy alongside audible sound, and the population is not experiencing the symptom cluster being attributed to data center infrasound. This is worth talking about and bringing up.

Criticism 6: Am I just a stooge for the data centers?

An honest skeptic could say many things about Jordan’s video. They could say his Finnish citation is misleading. They could say the heart-contraction paper he relies on doesn’t replicate. They could say his haunted painting experiment has design problems. They could say the audible noise pollution story is a well-established mechanism for the symptoms residents report, and that Jordan hasn’t demonstrated the effects of infrasound rise above this level. All of these would be defensible.

What an honest skeptic could not say is that Jordan’s sources, as a body, say the “exact opposite” of what Jordan claims. That is a specific claim about the literature. It is also false. The sources Jordan cites are, at worst, ambiguous or overreached-from. At best, they say roughly what Jordan says they say. They do not, as Masley has repeatedly asserted, diametrically contradict the video they are supposedly citations for.

I’m not convinced by any of the author’s prior points here, so I maintain that Jordan’s sources either say the opposite of what he claims (that infrasound doesn’t cause harm) or are completely unrelated to what he’s saying (that audible noise pollution causes harm, with no mention of infrasound). I would on Twitter sometimes use some hyperbole and blur these together into “all his sources say the opposite of what he claims” so I guess the critic’s right that when I do that, I’m wrong.

Masley has staked out a position that effectively equates to “data centers are an unmitigated good.” He writes in his response to Jordan:

✅ Data centers don’t waste water.

✅ AI artwork is without victims.

✅ Using ChatGPT is not bad for the environment.

His first statement is pretty clearly correct at this point. He’s generally right on item 3, although it is still difficult to find adequate clean power for data centers. But Masley has painted himself into such an ideological corner that he can’t even recognize the ethical issues posed by AI art and the artists whose work on which it is trained without compensation.

The iPhone caused a massive drop in the number of bank teller jobs in the US. I think it’s both true that this was an unfortunate consequence of the iPhone, but also that the bank tellers weren’t “victims of the iPhone.” Maybe this is a terminological difference, I don’t know, but I think it’s reasonable enough to not think it means I’ve been blinded by ideology. Similarly, as I say in the art piece, I think the correct opinion of AI art is that it’s as if someone went to a museum, looked at a lot of other people’s paintings, and then went and made paintings inspired by them but distinct enough that they don’t breach copyright. When I was young I used to draw a lot of Tolkien-like maps. They were different enough that if I sold them, I wouldn’t be violating copyright, even though I learned them basically exclusively from looking at maps at the beginning of Lord of the Rings books. I don’t think it’s a sign that I’ve painted myself into an ideological corner to say that I wasn’t harming the Tolkien estate here by doing this, and that AI doesn’t steal from artists by doing similar things.

Have I staked out a position that data centers are an unmitigated good? Also no. In the piece, I say xAI Colossus was bad and shouldn’t have been built, that the crypto mine data center in Texas was clearly really bad, and that noise pollution issues with data centers are very real. Leading up to this I was also posting a lot about how pollution and climate change are the other real issues I’m worried about. Again, this author doesn’t seem interested in what I actually wrote, he’s just lurching toward these big claims to denounce me.

Why did Benn Jordan share this?

I normally wouldn’t reply to criticism this bad, but I felt obligated to after Jordan elevated it in the discourse and his followers seemed to agree that it showed I was wrong. Again, he’s tricking his followers. Why, if this is so easy for me to dunk on despite not thinking about sound much day to day, did Jordan share it as if it’s all correct, despite working on sound all the time? I think it’s because he’s again being dishonest here and knows who’s right, and is just looking for another way to dodge the obvious fact that none of his sources said what he claimed.

Flashing my credentials

I don’t normally like to do this, but I’ll point out that of the three of us, I’m the one with the physics degree. The author seems to have a degree in architectural technology and design. I assume Jordan knows a lot more than me about audio engineering, but I’d kindly request that if you see a title that says Andy Masley doesn’t understand how sound works you treat it with some skepticism. I have a degree in this stuff and taught it for 7 years! If you look up “IB Physics” in YouTube, one of the first things you’ll see is a picture of my face. I claim that I do in fact understand how sound works.

A music rec

My favorite piece of low frequency music is Monoliths and Dimensions by Sunn O))). A top 10 album for me. I ended up listening to it a lot writing this and the last post. Check it out.