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Joined 1 year ago
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Cake day: August 15th, 2023

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  • Thank you for taking the time to explain, we do indeed seem to be closer to each other’s understanding.

    So the frequency of a repeated waveform and the shape of the waveform are not interchangeable. Hence my conclusion is that despite… theoretically the amount of energy may be the same, there is a difference in how the energy is transferred.

    This is contrary to what I remember having been taught about biomechanics and hearing, but as memory and understanding is unreliable, I’ll cede that I’d need to look up a reference for better precision.

    The crux of my argument hinges on there not being a difference. And my understanding of the physiology is that the hairs will primarily bend with pressure, and exhaust with flexion (repeated bending cycles leads to breaking), within the limits of survivable amplitudes.

    If there isn’t a difference, my argument continues in that it’s physically very difficult to create a pulse with a ramp up faster than the 20 kHz the ear is evolved to take, that’s 0,05 ms, not many physical processes go that fast to create a pressure wave and those that do typically get dispersed very quickly, unless as part of a harmonic excitation.

    But of course all that is irrelevant if that’s not how the ear reacts.

    headphones. Those limits are with respects of quality of sound reproduction.

    You may be right, the details of what the measure represents haven’t been presented.

    From context where it’s being argued as a legal argument, I have assumed it to be part of the safety design, and not of sound reproduction.

    Ear phones/plugs have no business reproducing good quality sound at >100 dBA, and would be sued into oblivion as the hearing damage and tinnitus reports rolled in. Which to be fair, is what the OP is about.

    Having a physical limit at 105 dB would then be congruent with the same unused overhead you refer to, as it corresponds to a doubling of potential sound pressure, and is about typical as overcapacity for high fidelity engineering applications.

    faulty earbuds that emitted bursts of painful high frequency noise despite playback being of moderate volume.

    105 dB would probably be painful, and as a surprise would be jarring, which contributes to the perceived risk of injury. It should also not be loud enough to cause lasting physical injury, and you’d typically have full functionality within two weeks.

    An earbud/head phone can be designed failsafe, so that casing, driver, or most commonly membranes will break at too high amplitudes. If nothing else, it will be limited by the amount of energy available, which for wireless or portable headphones is typically very low. I can’t vouch for the specific gear in the OP, but given the rarity of recalled gear due to injury, I’d guess it would be widespread industry practice to design it fail safe.

    What I’m saying is that it can still be hardware/physically limited at 105 dB, even though it gave a painful squelch before breaking.

    I apologize for my frustration. I’ve been experiencing lately that I try to communicate one thing and the recepient keep projecting it into their own frame of reference and insist I’m talking of something that I’m not. I’m a bit touchy and I’m sorry about that.

    I totally get it, it’s a built in flaw of the Lemmy/social media format. Too little supportive language cues, and too little time and/or investment to actually listen.

    I appreciate you having the patience to talk this through with me.



  • But good sir, a rapid change in pressure is the same as a high frequency sound wave.

    It makes little difference if it has a long duration (a tone, or noise) or short duration (a puff of air).

    And the higher frequencies neither carry more energy, nor are more damaging than lower frequencies.

    But you are right in that the ramp up in amplitude matters, and which could theoretically be over a very short time period either in frequency or duration with the same amount of damage. In ear plug practice this would however be limited by the electrical pulse in the driver (both wattage and Hz), and the viscosity of air flowing through the back of the speaker cavity.

    A significant ramp up is what is typically meant by high maximum instantaneous sound levels, LpFMax, and those are typically long term damaging at >115 dBA, unless other risk factors are present.

    (Just to be overly clear, I’m not faulting your use of language (once I understood what you meant), you’re doing admirably, and I fully understand that language is malleable and context dependent - I’m not hung up on the words.

    I’m trying to get to your understanding of the physics behind it, which I read as a little muddled. It could still be due to language barrier, but what I pick up is some confusion in the differences between frequency domain and physical domain.)

    On the other topics, which you seem to understand, but I’ll try to explain again to see if our models can better converge:

    On the topic of the tiny plunger, this is actually how virtually all speaker elements generate sound. You have a little element, called the driver, pushing on a membrane in the frequency and amplitude you’re trying to convey. The driver and membrane can’t be infinitely flexible or have infinite plunging depth, lest they need infinite energy to push an infinite amount of air, and so are typically carefully designed to certain specs, called dynamic range (frequency/speed of driver), and sound power (amplitude of driver).

    As to what the ear is designed for, it is actually very well protected against high frequencies, this is a large part of why we can’t hear higher frequencies than ~20 kHz. But you are right that it’s not made for sudden loud noises (a steep ramp up in amplitude). And although I don’t actually know, my motivated guess would be that human reaction time for the protection against sudden loud noise is at best 1/8 th of a second.


  • I’m also not a native english speaker, but I am however a professional acoustician. I’m not opposed to you defining your terms in a way uncommon to both acoustics and audionomy, and with this explanation they’re clear, although I don’t understand how the contrast is relevant to the topic. No matter how the signal is created, it will have to be a pressure wave of amplitude and frequency, travelling through a medium, like air, to reach an ear.

    However,

    Can headphones or earbuds or loudspeakers reproduce a digitally generated noise in frequencies that are painful in amplitudes that are harmful for the human hearing apparatus?

    Headphones and earbuds certainly can produce harmful amplitudes, that is why most of them are designed to be physically limited not to be able to. This is what the upper limit OP mentioned usually refers to, the maximum physical level the ear plug can produce. Limited by available airflow, membrane, driver, power, and seal.


  • Excellent question!

    The energy is typically dispersed by hairs moving, muscles moving, eardrum moving, soft tissue deforming, the hearing system behind the ear drum, your eustachian tube, the movement of the ear pod against your outer ear, and the imperfect seal of the ear pod.

    105 dB is probably the max sound pressure level at optimal seal.

    Also, it’s easy to verify, as resonance is literally the reason why violins, guitars and pianos have a ringing sound. Whereas regular sounds do not, because your ears don’t have audible resonances (they do have resonances in other frequencies though, just as your eye sockets, lungs and other stuff).


  • You’re almost right in so many aspects it unfortunately becomes utterly wrong.

    Digital and analog noise aren’t real things, or at least not the words that are used for it. Digital and analog noise has to do with signals and frequency spectrums, not with the actual pressure differentials that are physical sound waves.

    But there is a similar concept, where a thing happening can create a strong pressure wave, typically called an air blast, and are common when talking about blasting and other explosions (where the pressure wave is significant, but not really a noise). Ear pods do not create a significant pressure wave.

    The ear does have tiny hairs for hearing, and they do break at sudden and loud noises (@soleinvictus explained our defence mechanisms brilliantly in another reply) and also at repeated exposure to loud noises. A breakage typically results in partial, temporary, hearing loss and “ringing in your ears”, whereas permanent death of the sensory cells leads to tinnitus, which isn’t the same as hearing damage/loss.