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Old 09-12-2010, 12:42 PM
Confuseling Confuseling is offline
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Default What causes microphonics, anyway?

Having trouble finding a specific explanation for this (well, a coherent one anyway... ). Why does it happen in IEMs, and not 'cans'? Only explanations I can think of are that the driver is lighter and takes less energy to move, so more susceptible to vibration and electromagnetic noise, or that the size of the casing doesn't allow for magnetic shielding.

Part of it seems to just be the trapped air echoing when the IEM vibrates, but there seems to be more to it than that when the thing is actually on - though I could just be imagining it.

Anyone actually know?


Edit - Although having now just had a play, I'm more convinced I'm imagining it... It doesn't seem louder / different when they're on. This raises the question, if it's just having a plug in your ear with string attached that'll do it, what factors make it worse in some IEMs than others?

Last edited by Confuseling; 09-12-2010 at 12:51 PM.
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  #2  
Old 09-12-2010, 12:57 PM
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Actually because IEMs are in your ears, the vibrations pass on to your eardrums more audibly whereas for headphones they don't.

It's mainly due to cable quality, AFAICanTell.
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Old 09-12-2010, 01:11 PM
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Properly wearing iemís creates a seal with the ear canal and creates a mini acoustic chamber, thus if your iemís have poor quality cable they can transmit noise from anything touching the cable, such as it brushing against your clothing or anything else. To eliminate or reduce this bothersome noise you can wear the cable up over the ears and down the inside of your shirt, which helps tremendously on most cables.
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Old 09-12-2010, 02:46 PM
Confuseling Confuseling is offline
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Hmm... I wonder how much of it is conducted through the tissue of the ear, and how much of it is just the trapped air vibrating? There certainly seems to be a different, muffled, quality to the sound, a 'swimming pool effect' for want of a better term - maybe this is explained by direct transmission through solids? Or maybe it's just that having something in your ears blocks out higher frequencies. Not a clue.

I've taken to wearing mine looping behind my ears, and it's certainly better - as is using the cable clip. Never tried wearing them inside my clothes though - I'll have to give that a shot.

Thanks.

Last edited by Confuseling; 09-12-2010 at 03:04 PM.
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Old 09-12-2010, 06:56 PM
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for braided cables, you shouldn't hear a lot. I'll have to 'touch' the cable above my neck level to 'hear' the microphonics
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Old 09-12-2010, 09:29 PM
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Quote:
Originally Posted by Confuseling View Post
Hmm... I wonder how much of it is conducted through the tissue of the ear, and how much of it is just the trapped air vibrating? ... ...
Donít confuse cable microphonics as explained above with bone conduction, where the later is different. Bone conduction is a phenomenon where the IEM user can hear noise (caused by body motion such as eating and walking) transmitted with in the body to the ears acoustic chamber when the ear is plugged with iem's or custom monitors. BTW I added the explanations to the "Glossary" (link under my signature).
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Old 09-13-2010, 06:30 AM
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Note : Do not wear it inside your shirt if your IEM has cables that aren't tolerant to sweat.
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Old 09-14-2010, 05:26 AM
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Thanks for the tips - I've taken the plunge and ordered some of those Panasonic HJE900s. Arguably excessive when you don't listen to music, but I figure the clearer voices sound, the less fatigueing they'll be.
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Old 09-14-2010, 05:32 AM
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You might want to foam mod your HJE900s if you find the sibilance too much for your ears.
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  #10  
Old 09-14-2010, 05:39 AM
Confuseling Confuseling is offline
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I will certainly consider that - it's less wearing on a battery than using an EQ constantly. Will probably look at my options for new tips too.

Thanks again.
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Old 09-14-2010, 05:56 AM
CowonFTW CowonFTW is offline
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If you're asking HOW, eh, a grossly oversimplified (and probably wrong!) explanation is we convert pressure waves into mechanical vibrations via sensory receptors, so vibration in our auditory system is "heard", it's even mechanically transmitted via the malleus, a bone on the back of the timpanic membrane.

It wouldn't matter if it's an IEM, earplug, your finger, a pencil, or anything stuck in the ear canal. They're all the same thing as far as another device transmitting physical vibrations that become sounds. Which is why supra-aural won't pick up cord noise, but circumaural might, depending on how good the seal is and how tight the fit is.

As to WHY, it's mostly in the way IEMs are worn. Tip construction matters somewhat, the silicone "mushroom" tips transfer less motion therefore noise than flange tips, and everything is less conductive than the denser and form-fitting foamies. IEM construction probably doesn't matter much, although this is an observational assumption having worn many of them. Same for this idea of "cable quality" affecting cord noise, I'm 95.25% sure it makes no difference as long as it's still a little flexible audio-grade headphone cord.

The tip construction is more a factor if you wear your IEMs so that just the tips are the only contact, or IEMs that force you to wear them this way, like Ety ER4s. This tends to really amplify cord noise and make the wire a sensitive "transmitter" of friction and wind, and in this situation the cord construction might make a difference.

Push the IEM down where a normal earbud rests, behind the antitragus, and run the cord over the helix of the ear. All this skin contact dampens conduction, so cord noise farther down isn't heard. Many headphones have a cord slide, if you use this to make the wires touch you (draw the wires up behind the back of your neck with the slider like a backwards bolo tie), and/or use a cord clip, you can greatly attenuate or eliminate cord noise.
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Old 09-14-2010, 05:08 PM
Confuseling Confuseling is offline
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Great post - makes a lot of sense, so thanks. 95.25%, eh? Remarkable

Still not entirely sure I grasp why a super-aural headphone won't, and a circumaural might - because circumaurals [potentially] create a trapped pocket of air too?

I've been thinking a bit about this, and I guess the bone conduction bit is audible just because the normal soundscape is missing, much like a Weber test for unilateral conductive hearing loss.

Interesting stuff - and not something I've ever really given much thought to before. Not really my field...

Last edited by Confuseling; 09-14-2010 at 05:14 PM.
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Old 09-16-2010, 08:32 PM
CowonFTW CowonFTW is offline
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LOL you and that air pocket concept. I'm sure there's some truth to it, but conduction is conduction, be it air molecules or bits 'o human. It's conduction - energy transfer. RE: the phones, it's because one sits on your soft squishy ear and is (essentially) mechanically decoupled, and the other sits on your thin skin that's stretched over your skullbone. :^P
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Old 09-17-2010, 11:59 AM
Confuseling Confuseling is offline
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Conduction may well be conduction, but waves change as they move from one medium to another - case in point refractive indices, diffraction... The trapped air must make a difference, unless you have a better explanation as to why correctly fitting IEM tips suddenly produce bass, whereas loose ones don't? I doubt it's direct transmission through the flesh of the ear canal, but then I've been wrong before...

Last edited by Confuseling; 09-17-2010 at 12:08 PM.
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  #15  
Old 09-17-2010, 03:42 PM
CowonFTW CowonFTW is offline
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Certainly! I'm not debating the air chamber as an enclosed area of molecules to vibrate, but it's role in microphonics is what I doubt. Obviously this trapped air exists unless you have a REALLY technical method of inserting your tips!
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