Do you mean it makes no sense to you? It is not a claim, it is a statement objectively describing something. PWM, or pulse width modulation, obviously has... pulses, a width to those pulses (length of cycle), and a modulation factor (depth of cycle plunge). How a manufacturer implements these variables matters, as does the light source for the flashing light.
Your statements are not easily understood as objective descriptions because you're using lots of strange, nonstandard terminology. The three main terms engineers use to discuss PWM waveforms are duty cycle, pulse width, and modulation frequency. I have literally never heard anything like the phrase "depth of cycle plunge" before, and keep in mind that I'm an engineer who's used PWM many times during my career.
Also, when your intent seems reasonably clear despite the odd phrasing, there's lots of hints that you've misunderstood basic PWM concepts.
"the consumer" is not one person - and as you know, people are all different. In fact, even if you aren't, other people are PWM sensitive, hence the community named "PWM_Sensitive" and the ability for some people to notice and post about it.
Perhaps you are not sensitive to this issue? I'm not sure where the disconnect is otherwise, I'm not trying to convince you that you are impacted in any way. It is possible you do not notice or mind PWM, as the majority of people do not seem to have an immediate reaction to it.
Yes, of course people are different. However, there's limits to how different they can be.
Usain Bolt set the current world record 100m dash time in 2009. During that race, his peak measured speed was nearly 28mph. It's very safe to say that no human will ever double Bolt up and be clocked at 56 mph. We're not cheetahs, our body plan is biomechanically incapable of running that fast.
The same thing applies to eyes. There is a range of plausible performance variation based on human eye anatomy and chemistry and so forth. What we're talking about here goes far beyond that.
One working theory among researchers is that COVID can lower a person’s critical flicker fusion threshold.
Is this coming from real scientific researchers, or forum posters whose main tools are Google and AIs and other sources of confident misinformation? I have to ask because I do know a little bit of relevant info about how eyes work, and it doesn't seem compatible with this idea at all.
Important caveat: I am not a real expert or researcher in this field either. I'm a digital design engineer. Thanks to my career path I've worked alongside PhD biologists and chemists, and I've absorbed miscellaneous info from them. But that has obvious limits. No formal training here, I'm only a guy who's helped biochemists out with the computerish stuff they needed to enable their work.
That said, let's get on with a more in-depth look at this idea. You've used language ('lower' the flicker fusion threshold) which hints you think COVID decreased the performance of your eyes in some way. When stated that way, the idea seems plausible enough to consider. However, the truth is that this idea actually requires COVID to massively
enhance eye performance in certain ways.
The process of perceiving light involves photons (light) being absorbed by photopigments in the rod and cone receptor cells in your retina, altering the pigment. The presence of altered photopigment molecules then triggers a cascade of other chemical reactions, which ultimately change the rod or cone cell's output firing rate to signal other neurons.
Human biochemistry is quite slow relative to transistors and light emitting diodes. When PWM light pulses are short and frequent, these chemical processes can't match speed. In basically any kind of physical process, when a stimulus is varying too quickly for the slower process to track it directly, the process averages and smooths out the waveform. That's how PWM LED brightness control is able to simulate dimming without ever running the LED in states other than full brightness and off. Works quite well so long as the modulation frequency is literally too high for your eye's chemistry to follow.
Which begs the question: how high is enough? Here we can turn to empirical test data. In humans, flicker fusion starts to happen at double-digit Hz. This is why 50/60 Hz TV works fine. That said, it's not a simple story and many effects are perceptible well into the hundreds of Hz. There's valid reasons why 144 Hz refresh monitors exist, they aren't totally pointless. I'm also aware of some scientific research that demonstrated exceptionally high performing individuals are able to perceive specific kinds of one-shot optical events at time scales down to ~1ms, equivalent to 1000 Hz. As far as I know, this is a number we can reasonably take as the upper limit of normal human potential.
With that ~1000 Hz number and the ~15000 Hz PWM frequency of MacBook LCD backlights in mind, let's restate the hypothesis: Could COVID
greatly raise (not reduce!) the frequency threshold beyond which your eye's photoreception processes smear individual PWM pulses into each other?
A further rephrasing: could COVID grant you photochemical / neurological superpowers? Yes, superpowers. That seems to be what it would take; lots of eye biochemistry would somehow have to run about 15 times faster than normal. If this was a 100m dash, it'd be like hitting 420 mph.
(Okay, okay, there's all sorts of ways that analogy breaks down. For example, unlike sprinting, so far as I know you can't do some kind of eye exercise regimen to greatly improve your personal flicker detection performance. But I think that only reinforces the conclusion that this idea isn't just a little bit out there, it's
really out there.)
I want to make it clear that I don't mean any of that to be taken as an insult. You're experiencing very unpleasant symptoms, and I'm not doubting or mocking that in any way. Nor do I think it's crazy that the idea sounded plausible to you. Most people don't know enough about PWM and eyes and so forth to reason their way towards skepticism. But at least from my admittedly not-a-real-subject-matter-expert viewpoint, I see lots of reasons to be skeptical, so I think you're barking up the wrong tree. What the explanation for your symptoms might be, I don't know, but it seems unlikely to be PWM.
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