[dura]

The same reason why speakers have cases, to avoid cancelation between the front and the back.
A speakercase is basically a wall to seperate front and back folded for convenience.
Once you have a seal you reach an infinitely large wall between the front and the back of the canalphones.
Break the seal and the wall is reduced to a few mm, and low frequencies are cancelled out.

 

[JohnRich]

Quote:

Originally Posted by hawkfire hello, the answer in short is simple. ... No external air is needed to bring the diaphram back to position 0 for response as is the case with dynamic drivers. armature drivers for eims, well The Etymotics er4p/s and er6 series use them The Shure E1, E2, E3 and E5 series use them. The Westone Um1 and 2 series use them The prophonics and ultimate ears lines use them as well. only ones that dont to the best of my knowledge is Sennheisser IEM3 aka futresonics EM3. These are the only IEMS that i know of. If there are more, enlighten me and tell me what other IEMS there are and what designs they use. That would definitely be interesting to find out and see as far as advances go in IEM design. thanks

The Shure E2 uses a dynamic driver not a b/a

 

[setmenu]

Perhaps this cavity resonance calculator will will be of more help in demonstrating the effect of leaks [ports].



http://hyperphysics.phy-astr.gsu.edu...cavity.html#c4

To begin enter figs to roughly approximate the ear canal volume such as 2 cc and then play with port size, for example 0.01 cm for area and 1cm for length.


Setmenu

 

[nikongod]

something that i dont think anyone here has mentioned is that bass is nondirectional. a low frequency cound canot be pinpointed by the human ear. similarly, you can not isolate a low frequency sound to a portion of a room, it is equally loud in all corners/areas. base generally "fills" a space. a larger space requires more power, generally.

high frequency sound is HIGHLY directional. if you are "behind" a high-frequency driver, unless the sound bounces off of a wall, or you are listening to he "back" of the driver (yes, the backs of speakers make sound too.) you dont hear that part well. a low power high frequency driver can be heard clearly for some distance, if you are in line with it. step out of line, and you loose the sound.

in order to get the nominal sound of the base to "regester" it has to fill a sealed cavity, the space between the eardrum, and the drivers in this case. if there is a "leak, the base litterally escapes. you can clearly hear the high frequency parts of the music with yoru phoens at a comfortable volume, and about inch from yoru ears if you aim correctly.

 

[aluren]

life is so complicated isn't it? how come the simple explanation of sound leak when there is no complete seal work? its like flushing your crap down the toilet. if the drain is clear, everything flushes down. if not, then some floats back up. think of bass as the crap and canalphones as the toilet.

 

[hawkfire]

hello,

To answer jmmmms response, he is absolutely incorrect in his statement of fact as shown here.

1) Vacuum only has one definition. It does not differ between science and acoustics. It is impossible for the pressure inside our ear canal to be different from atmospheric pressure. You know why? When you move your jaw, a tube opens within your airway that equalizes pressure on the inside of your eardrum. That is why you chew gum when on a plane. If the pressure difference was more than a couple lb/in2, the movement of your eardrum would be reduced, and so would your ability to hear. There is NO VACUUM involved in any of this. Note: This is NOT A GUESS

IT is indeed a guess on your part as there are many different definitions of vacuum. Accoustics, physics and electronics are but a few.

Let me explain in simple terms.

Vacuum=The condition of reduction of pressure below that of the atmosphere.

Because of this vacuum as defined above, ety and shure triflanges are able to stay in place.

There is no undo pressure at all on the eardrum because air inside the sealed cavity is lower than that of the amosphere. Vacuum doesnt become suction on the eardrum until YOU PULL on the earpiece itself without breaking the seal.

This is how ety users who arent careful in removing thier triflange tips hurt themselves by creating excessive suction from vacuum.

Vacuum and seal is the reason why there is a sound difference between using the foamies and the silicones/customs or triflanges.

Dura has it right as well.

And john rich, my oversight.

The Shure e2 does use a dymanic driver.

I just typed the post off the top of my head is all.

and mem24, vacuum is very much relevant to sound reproduction and iems as to lose vacuum is to comromise your seal and losing seal integrity=no bass and reduced treble and high response.

Also, I use circumaural earphones as an analogy to show an iem is supposed to emulate an full sized headphone in principle by utilizing the shape and length of the earcanal as a sound chamber for frequency response whereas circumarual headsets do this with a cup.

Not to prove a point of vacuum.

 

[Jmmmmm]

Quote:

Originally Posted by hawkfire hello, To answer jmmmms response, he is absolutely incorrect in his statement of fact as shown here. IT is indeed a guess on your part as there are many different definitions of vacuum. Accoustics, physics and electronics are but a few. Let me explain in simple terms. Vacuum=The condition of reduction of pressure below that of the atmosphere. Because of this vacuum as defined above, ety and shure triflanges are able to stay in place. There is no undo pressure at all on the eardrum because air inside the sealed cavity is lower than that of the amosphere. Vacuum doesnt become suction on the eardrum until YOU PULL on the earpiece itself without breaking the seal. This is how ety users who arent careful in removing thier triflange tips hurt themselves by creating excessive suction from vacuum. Vacuum and seal is the reason why there is a sound difference between using the foamies and the silicones/customs or triflanges. Dura has it right as well. And john rich, my oversight. The Shure e2 does use a dymanic driver. I just typed the post off the top of my head is all. and mem24, vacuum is very much relevant to sound reproduction and iems as to lose vacuum is to comromise your seal and losing seal integrity=no bass and reduced treble and high response.

Sorry buddy, but you are still wrong. Repeating yourself without backing it up does not make you right. First of all, if there are other definitions than the ones given of 'vacuum', please give them to us, and quote a source, please. The only definition that didn't say 'void of air' said a significant difference in air pressure. So lets give you the benefit of the doubt and say there is lower pressure inside the canal here. If there is this lower pressure, how exactly was it created? Explain that to me. The only way to create a lower pressure area is to either remove air molecules while keeping the volume constant, or increasing the volume while keeping the number of air molecules constant. The only way for the pressure to be lowered in this situation is if the canalphone actually sucked air from your ear canal and moved the air outside after you inserted it. That obviously doesn't happen. And I'll repeat again, if the pressure inside the ear canal is much different from atmospheric pressure, eardrum movement will be reduced, and so will your ability to hear. I doubt this is the aim of canalphone manufacturers. Most likely, the pressure is a tiny tiny bit lower inside the canal, created from the small movement outward as the canalphone situates.

What you claim is this vacuum inside your ear keeping the canalphone in place, is most likely a combination of a few things including friction between the earbud and your epithelium, and the fact that if the canalphone starts to move outward, the volume inside the canal increases while the amnt of air inside remains constant, creating lower pressure inside the canal, preventing the earbud from moving. You are sort of right about the 'vacuum' being responsible for the ety removal injuries. This is probably caused by, when removing the earbud with the seal still intact, you are increasing volume while keeping the # of molecules constant, therefore decreasing the pressure, causing the 'pop' and possible injury to the eardrum.

Dura's explanation seems reasonable, though I don't completely understand it.

 

[Cyclone]

either way your all wrong vacuumes are too big to fit in your ears.

corny joke-ended

 

[acklee]

All your vacuum are belong to us. Are we done arguing about semantics yet?

To go back to the point of the thread, from my uninformed standpoint, it makes sense that a closed volume of air is necessary to make the bass audible. Think about one of those water syringes - when you press on the plunger, you push on the water so it squirts out the hole. Try covering the hole with your finger, and you'll feel the water push on your finger.

Now imagine that the plunger is the canalphone driver, and your finger is the eardrum. In this analogy, you hear the bass by feeling the air being pushed against it. We're not talking about a lot of force here - just a tiny amount to move the air against your eardrum.

But if the seal isn't tight, then as the driver pushes the air, it goes straight out the hole instead of transmitting those tiny vibrations to your eardrum. Think about a water syringe with a hole in the side... as you press on the plunger, water goes squirting out the side hole, and your finger doesn't feel anything.

Just speculation, but makes sense to me.

 

[mem24]

Quote:

Originally Posted by hawkfire and mem24, vacuum is very much relevant to sound reproduction and iems as to lose vacuum is to comromise your seal and losing seal integrity=no bass and reduced treble and high response.

My apologies. If indeed the difference in pressure serves the purpose of keeping the canalphones in place, and isolating the cavity, then the point is relevant.

However, I'm going to have to agree with Jmmmmm, on the basis of user reports (travelers on airlines), that too great a difference in pressure causes the eardum to be unresponsive. I don't think we need to go as far as to say that this particular vacuum explains how the canalphones are held in place. Friction or even suction between foam/silicones/triflange and the walls of the ear canal could be sufficient.

At the same time, equalization apparently does not occur quickly by itself: people have to chew gum or pinch their nose and blow. So the cavity can still be pretty much isolated, without having a difference in air pressure relative to the outside.

Seems like a good analogy acklee. Wonder if oluv lost interest...

 

[mico730]

Alright guys, arguing on vacuum ends right here...

Let's go back to high school(or college maybe), the Ideal Gas Law says PV=nRT, remember that?? So, if you're saying pressure in your ear is reduced(vacuum), to maintain constant, either volume has to increase, temperature has to decrease or no. of mole of gas molecule has to decrease.

Well, after plugging in your canalphone, I assume your ear canal won't become bigger right?? And I don't think the air in your ear canal will cool down, or there'll be air molecules sucked out of it.

So, there's no way a reduced pressure (or "vacuum") can be created simply by plugging your IEM into your ear canal.

 

[Cyclone]

Quote:

Originally Posted by mico730 Let's go back to high school(or college maybe), the Ideal Gas Law says PV=nRT, remember that?? So, if you're saying pressure in your ear is reduced(vacuum), to maintain constant, either volume has to increase, temperature has to decrease or no. of mole of gas molecule has to decrease.

TRANSLATION: I took alot of A.P. classes in high school

 

[hawkfire]

hello,

jmmm,

By reading your responses it is painfully obvious you have either limited or no experience with any canalphone that utililizes a triflange or custom seal.

The Shure E2 doesnt fit this category.

And it seems you wish to be argumentative instead of positively contributing to this thread based on my observations.

Thats your perogative.

Micro730,

Well, after plugging in your canalphone, I assume your ear canal won't become bigger right?? And I don't think the air in your ear canal will cool down, or there'll be air molecules sucked out of it.

The opposite occurs.

And you just dont stick silicones or triflanges in and thats it.

You stick them in and then slightly pull out to seat them properly.

 

[setmenu]

If you want to demonstrate the effect of occlusion and the effect of a progressively increasing air leak , simply plug your ears with your fingers and hum a low note then slowly uncover the ear and listen to the change in the
perception of the level low frequencies in the hummed note.

As for canal phones being held in place by vacuum, nonsense

Setmenu

 

[oluv]

Quote:

Originally Posted by mem24 Wonder if oluv lost interest...

no no, i am still following. but most of my assumptions were already confirmed. well the discussion got a bit out of hand by arguing what a vacuum is and what not...

but most of the statements, especially about the enclosed air, inside your ear-canal that is needed to reproduce the lower frequencies is quite plausible.