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Things to consider before getting your custom IEM impressions done. The perfect fit.

post #1 of 64
Thread Starter 

 

I've recently had a few sets of impressions made and tried different sets of IEMs made from them. Here are my tips for those looking into custom IEMs. I spent a lot of time talking to my audiologist, doing research and have experienced the differences that different jaw positions can have on the end result.

 

The quickest and easiest way to get a good seal is to recommend use of a bite block during the impression. This recommendation is not always the best one however and can lead to an uncomfortable fit for some (especially if the wrong size is used). 

 

How jaw motion affects the seal:

 

When you open your jaw, the back of your jaw bone pushes up on your ear canal changing its shape. Because of the way this shape change occurs it is more likely that impressions taken with the jaw closed will cause the seal to break when the jaw opens. This also means if you take the impression with your jaw open, when you close your mouth you'll feel greater pressure from the IEMs in your ears than when you open your jaw. The "perfect comfort" point will be the position your jaw was in when the impressions were taken.

 

Things that effect your jaw position and thus your ear canal shape:

 

  • Leaning forward (jaw slides forward slightly)
  • Leaning backward (jaw slides backward slightly)
  • Lying down (jaw slides back a lot)
  • Clenching your jaw (never do this on a bite block)
  • Relaxing your jaw

 

Notes on bite blocks:

 

Bite blocks usually have two positions a horizontal and vertical. Their purpose is to keep the jaw stationary so the mold will be accurate. You do not want to be moving your jaw during an impression at all. That said, you also never want to bite hard on a block. If you use a block, hold it as lightly as you can between your teeth and try to relax as much as possible. The vertical bite block position (larger) is a bit overkill for most people and my audiologist didn't recommend it.

 

I did not use a bite block to get my "perfect fit" but I did hold my jaw relaxed and very still during the impression. Don't talk to your audiologist or move during the impression if you are not using a block. Focus on keeping the angle of your head at the desired angle and not moving at all. Without a bite block in your mouth, tilting your head will move your jaw position if your jaw is relaxed. If you aren't sure if you can keep your jaw very still for about a minute straight you should probably go with the block.

 

My first set of impressions were taken with a bite block in the vertical position (large) and resulted in an IEM shape that  never really got comfortable.

 

bite_block.jpg

 

How to to maximize the comfort of your custom IEMs:

 

The tips i'm mentioning here relate specifically to comfort only. Comfort does not always equal a solid seal although it can for some people. You have to have a seal for a successful set of IEMs obviously, but there is such a thing as too much seal when it is to the point where the pressure causes discomfort.

 

Ideally for a comfortable fit you should hold your head and your jaw in the "average" position that you will hold them in when using your IEMs.  In my case, I am an audiophile who does not sing. I tend to listen sitting leaning forward slightly while using the computer or when laying down. I don't talk when I listen to music, and I don't eat with IEMs in. This makes my average position sitting up straight with my head just ever so slightly tilted up/back and my jaw relaxed (teeth apart) but not forced open.  This position yielded an amazingly comfortable fit for me, i don't even feel my IEMs in my ears after about 5 minutes. Luckily in my case this also produced an excellent seal.

 

If you are a singer, take note of how wide you open your mouth when you sing. You likely don't need to take the impression with your jaw open at 100% of where you tend to open it at its widest. Again you want that "average" position. This will be the position your jaw is in the most when you use the IEMs.

 

If you only listen to your IEMs lying down on your back, have your impressions done while you lay on your back. In short, do whatever it is you'll be doing the most when you use your IEMs.  If you do multiple things while using your IEMs, find your average position between the two and use that.

 

Get a complete ear impression in and out:

 

Have your audiologist include everything shown below (except the Lobule) in the mold as it makes life easier for the technician working on your IEMs and they need this detail for positioning the wire outlets and properly molding the entire IEM. Ask your audiologist  to use the high-viscosity type of silicone for the mold as it will form a better quality high-durability impression and will render a better acoustic seal.
 
 
stl502346.fig1.gif

 

All ears and jaws are different:

 

In my case I took my second set of impressions with my jaw relaxed and my lips just barely apart. Even if I open my mouth ultra wide, I still don't break the seal on my IEMs. If I was a singer I would be fine with the impression I am using currently only for audiophile use. In fact, there is nothing I can do with my jaw position to break the seal. Not everyone may have the same experience however.

 

The amount that the ear canal is affected by jaw movement will vary from person to person.  Most IEM companies will instruct you to use a large bite block. It essentially guarantees a good seal, it just may not end up being a comfortable one for all people. In these cases they will often revert to recommending a less open mouth or even a closed mouth impression.

 

Hopefully this helps some of you trying to attain that "perfect fit." 

 

If you have had a different experience or have your own information to share please do add it to the thread!

 

 

 


Edited by Sproketz - 11/5/11 at 10:02pm
post #2 of 64

good info, ty

post #3 of 64

I'll also add, from recent experience, it's worth ensuring you candidly discuss with your audiologist that you'd appreciate him/her pressing the silicone thoroughly into the external portions of the ear - mine didn't, and although the impressions were usable (the canal portions were excellent), the silicone didn't completely come into contact at some points of the external ear, which is far from ideal.

 

If you look on Youtube, you'll see what I mean about pressing the silicone - search for 'Ultimate Ears Fitting'

post #4 of 64

I had 6 sets of impressions done over the years. My best seal was full open mouth with large bite block. All others lost seal as my jaw moved.

post #5 of 64
Thread Starter 
Quote:
Originally Posted by Mython View Post

I'll also add, from recent experience, it's worth ensuring you candidly discuss with your audiologist that you'd appreciate him/her pressing the silicone thoroughly into the external portions of the ear - mine didn't, and although the impressions were usable (the canal portions were excellent), the silicone didn't completely come into contact at some points of the external ear, which is far from ideal.

 

If you look on Youtube, you'll see what I mean about pressing the silicone - search for 'Ultimate Ears Fitting'



Good suggestion. I updated the post above to add this information. Thanks for that. My audiologist did a huge impression which basically covered the entire surface area of my ear.


Edited by Sproketz - 11/6/11 at 7:06am
post #6 of 64

Great thread and super info guys.  Thanks for sharing your insight.

post #7 of 64
Great advice!

I found using the bite block horizontally got me phones that could have a little more of a seal sometimes...

But my last pair of impressions were done with the bite block vertical, leading to quite a wide opening of my jaw. It yielded some earphones that were not overly uncomfortable, but they put a bit more pressure all throughout my inner ears than I had hoped.

For my next set, I'm going to try and figure out a way to get a gap somewhere between the 2... maybe the horizontal bite block with something else as well.
post #8 of 64

This is approximately how a decent ear impression should look:

 

For an example of an inadequate ear-impression, please see discussion here:

 

http://www.head-fi.org/t/684396/new-jh-audio-flagship-siren-series-roxanne/1275#post_10056821

http://www.head-fi.org/t/684396/new-jh-audio-flagship-siren-series-roxanne/1290#post_10056903

http://www.head-fi.org/t/684396/new-jh-audio-flagship-siren-series-roxanne/1290#post_10056929

 

 

 

 

 

 

For those folks reading this thread who are new to custom IEMs, in addition to Sproketz' excellent advice, you may find the following clips on Youtube to be of interest:

 

 

And here are a couple from 1964 Ears (thanks, average_joe & tomscy2000, for the links):

 

 

Please note that although these are from UE's, Westone's, and 1964 Ears' production facilities, the same principles apply to anywhere acrylic-shelled custom IEMs are made (with the slight exception that some vendors choose to inject a silicone or acrylic FILL into the acrylic shell, once the drivers/crossover/wiring have been fitted. M-Fidelity, for example, inject silicone into their SA-43 hollow acrylic shell, and FitEar inject acrylic into their CIEMs, so the end result is a FitEar acrylic CIEM with no air inside it, just components and solid acrylic.

 

CIEMs made entirely from silicone require a substantially different production process, but I've yet to see any videos detailing that. If I do, I'll update this post.

 

 

...and examples of the impressions procedure can be found here:

 

(I disagree with the bite block being used in the maximum-opening position, as seen in this video. It leads to too much tension in the jaw muscles and would only be really relevant for opera singers, or rock vocalists who scream with their mouths wide-open whilst using their CIEMs. I only use the bite block in the medium position and get good comfort and excellent seal, even when opening my mouth whilst listening to the CIEMs).

 

 

and here:

 

http://www.rockstarears.com/earimpressions.html            (the customer/patient in this video is doing it all wrong - moving around all over the place, grinning, stooping down... really a textbook example of how not to have ear impressions taken. It's not the audiologist's fault, just a naive customer. To get the best possible results, one needs to be as absolutely still as possible).

 

 

Keep in mind that if you have a perforated eardrum (see your doctor!) or  impacted earwax, the audiologist will be unable to take impressions. Therefore, if you already know that you have issues with earwax, for example, you may save a wasted appointment if you make some effort to address the issue during the week prior to your appointment. You can purchase over-the-counter products for breaking down accumulations of earwax, usually in the form of ear drops (e.g. 'Otex'), or you can simply use (clean!) olive oil, applying a couple of drops a day. If you're unsure about this, then simply see your local doctor or pharmacist.

 

 

Also remember it will be easier for all concerned if you take with you some printed guidelines (both for yourself and for the audiologist) relating specifically to impression-taking for the purposes of custom IEMs:

 

jhaudio.com/files/Audiologist-Tip-Sheet.pdf

 

nobleaudio.com/support/impressions-instructions

 

 

I noticed the following link was also posted on frogbeats' website:

 

audiologyonline.com/articles/earmolds-and-more-maximizing-patient-850

 

 

(Remember: the above 2 instructions links are intended for Acrylic CIEMs. If you are buying Silicone CIEMs then the instructions are the same except that the vendor will probably request that you keep your mouth closed during the impressions-taking procedure)

 

Very rarely, an acrylic CIEM vendor may request a different method of having impressions taken. I don't know if Fitear do their impressions differently depending on whether you are a singer or an audiophile, but, apparently, they request the customer to move their jaw slightly whilst the silicone impression material is curing (http://www.head-fi.org/t/607362/new-fitear-mh335dw-custom-iems/60#post_9089125), but (unless you purchase via a 3rd-party dealer like Jaben), they will insist on you visiting their premises and doing the impressions personally, with their own staff, so this unusual exception doesn't negate the advice in this thread, for having impressions done for almost all other acrylic CIEM vendors, via an independent audiologist.

 

UPDATE: I have recently heard that Hidition may ask for impressions to be done with the mouth closed, even though they make acrylic CIEMs. However, it may be that they make their CIEMs slightly larger in order to achieve a very snug fit. Please do always check with the vendor you are ordering your CIEMs from.

 

 

 

 

It's also worth taking along a bite block of some sort, to be prepared in the (admittedly unlikely) event that the audiologist doesn't have any to hand (this should not be hard, as it may be uncomfortable to bite - balsa wood, polystyrene foam, a chunky pencil eraser, or similar would be OK. On my second occasion, I had to improvise by biting the side of my hand, but this is obviously less than ideal!

 

Also take a handkerchief/tissue in case you find yourself drooling whilst the bite block is in your mouth.

 

The silicone doesn't take long to go off (5-8 minutes) and the experience is not unpleasant, so just relax and try not to laugh or smile while the audiologist is grinning at the sight of you gawping with a bite block in your gob and drool running down your chin blink.gif heheh.

 

 

More Head-fi discussion:

 

http://www.head-fi.org/t/470450/custom-iem-impressions-gone-wrong#post_6372502

 

 

Also, of related interest to CIEM buyers, (although not directly related to having impressions taken):

 

Functional Anatomy of a BA drive unit:

 


Edited by Mython - 4/17/14 at 7:01pm
post #9 of 64
Thread Starter 

Awesome vids Mython. I hadn't seen the creation process this in-depth before. Very cool.

post #10 of 64

Yeah, the hollow UV acrylic in the silicone mould is particularly cool - I'd often wondered how they went about doing this (I was previously wondering if it was done with a 3-D centrifuge, as is the case with certain types of hot plastic moulding), but no... time-controlled UV exposure; what a great idea.

 

The main question I have after watching those vids is why UE sometimes use laser scanning and sometimes use the hotwax-dipping method. Why the disparity? Obviously, they'll use the computer method if an audiologist sends them a 3-D laser-scan file digitally, via e-mail, instead of shipping a silicone impression, but that can't be the only circumstance under which UE are using that laser set-up because they have a scanner right there, in-house. Presumably, 3D printing of the laser scan is a more expensive process than the conventional, manual, wax-dipped silicone impression method, but still, that's no conclusive answer.

 

I'm also curious how they phase-align the various BA drivers in the shell - do they simply place the BA drivers in the shell the best way they'll fit, and then attempt to phase-align them electronically? I'm not sure that's possible, and yet there seems to be a wide disparity in BA driver placement, if one looks at photographs of various makes and models of custom IEMs.

 

Questions, questions! confused_face_2.gif rolleyes.gif


Edited by Mython - 11/5/11 at 10:37pm
post #11 of 64

Great write-up. Thank you for sharing this.

post #12 of 64

Great info very detailed and informative

post #13 of 64

Good thread & info, thanks!

 

You might also want to consider these two threads:

 


 

Quote:

About health issues. Blu Tack is actually recommended by doctors.

Beware I'm NOT a doctor though. All I can testify is that I have been using successfully wax earplugs to block outside noise for 20 years, yet, I'm switching to Blu Tack even for that: I find it less sticky and Blu Tack seems to remain cleaner than wax earplugs. Plus, it's damn cheap. Plus, I find it even harder that a tiny ball might remain inside, as it melts into a solidly compact ball.

I know that earplugs aren't for everybody though. They just have worked wonders for me all over the years. I have tried many different brands, even rubber earplugs, and none come close to Blu Tack in terms of ease of use, vacuum sealing and even safety.

Some additional information:

Post-operative care

Water Care


"With ventilation tubes in place there is a concern that if water enters the ear canal, it may pass through the tube and into the middle ear, and set up an infective process in this area. This is not an inevitability, and some patients with VT"s swim and shower or bath without protection and never have a problem. It advisable however to take some precautions. Simply this involves the use of earplugs (blue tac, cotton wool and vaseline, silicone ear putty, or custom made plugs)"

Source: Surgery. Myringotomy and grommet insertion.

Blu Tack as been very popular among surfers over the years, to prevent water from entering the inner ear.

For surfers though, their problem is that Blu Tack blocks too much sound!


Blu Tack seems to be evaluated in this medical study too, though it's not publicly available:

Ear protection against water-borne infection: an objective evaluation
The Journal of Laryngology & Otology (1986), 100: 1337-1340 Cambridge University Press
doi:10.1017/S0022215100101100

Abstract

Eight different ear plug materials were tested, in 5 ears each, in artificial shallow underwater conditions for 30 minutes, in order to determine their efficacy in sealing the ear canals to avoid water-borne infections in ear canals and open middle ears. Most of the plugs tested would meet everyday requirements for protection, but the polymeric foam plugs, treated with petroleum jelly, and moldable plastic materials were most effective in protecting both the middle ear and the ear canal skin.

Yet another study:

Mitchell, I. C. (1991). "'Silicon ear wax' and 'Blu-Tack' ear-plugs," Med. J. Australia, May, 154, p. 712. /998/

This seems to be safe and tested enough.

Again, be warned I'm NOT a doctor. Just a waaay happy audiophile now.


Finally, some pics:




I'm willing to bet that this is EVEN BETTER than having a custom fit done for you by an audiologist. As we know, there are loads of people who have to go back to the audiologist to get a proper seal. Even when they do, as we all know, the shape of our ears change with time, due to several reasons, sudden increases in body fat and so on.

Blu Tack guarantees that you will always get a proper seal for HOURS, without any risk of infection for your ears.

Let me know how this works for you if you try this.


 

 

Forget the audiologist! Audiophile Holy Grail Heaven for just 1$. Blu Tack and In-ears: BEST. HACK. EVER.

http://www.head-fi.org/t/299863/forget-the-audiologist-audiophile-holy-grail-heaven-for-just-1-blu-tack-and-in-ears-best-hack-ever

 

 

 

 

and:

 

 

 

Quote:
Originally Posted by Nightslayer View Post

I recently purchased a pair of Westone UM1s after I lost my Crossroads Quattros, took rather long to get used to the rather bass-deficient sound but I was quite happy with the overall sound signature. Switched from the comply tips to the Shure Olives, and found that that helped a bit. Then I was looking around and found this:

http://www.head-fi.org/forum/thread/466222/diy-guide-making-your-own-custom-iem-sleeves-tips-56k-get-outta-here

and this:

http://www.head-fi.org/forums/f4/custom-ear-molds-pics-course-212962/

Well I thought it was rather interesting to try out, but I lacked the money to go to an audiologist to get a bunch of ear impressions (paying a third of the price of the earphones for an experiment? I'd rather not) and didn't have the balls to stuff epoxy in my ear like that madass in the second thread, due to me coming across forums which warned against stuffing anything into your ear whatsoever.

 

I decided to try to make my own ear impressions using blu tack (figuring it wouldn't be that bad), and after a bit of trial and error I actually got something approximating a pair of impressions. DSC05363.JPG

I coated them with nail polish and tried out the steps which the guy in the first link did, but then I discovered working with silicone and oil is a horribly messy process, not to mention not for someone impatient like me. Aside from getting almost uncured silicone in my right nozzle (which thankfully didn't impact the sound once I removed the waxguard, I was panicking like crap), removing half-cured silicone from a silicone mould turned out to be a lot harder and messier than I expected.

 

After a while I came across another thread in which the guy replaced his eartips with blu-tack and actually liked the sound:

http://www.head-fi.org/forum/thread/299863/forget-the-audiologist-audiophile-holy-grail-heaven-for-just-1-blu-tack-and-in-ears-best-hack-ever/30

so I decided heck-it-why-not and started trying to poke a hole through the impressions I had, and then dig out a bit of blu tack to form an outline of my UM1s and stuck it in. And the result would be:

DSC05362.JPG

Yeah green and pink don't really go, but I'm a guy and I couldn't get my hands on black nailpolish. ><

DSC05357.JPG

The earphones stick out a bit more now out of the ear though.

DSC05379.JPG

Sorry for the slightly blurry quality, phone cam with my left hand >< But it fits like actual customs.

 

Sound signature wise.. IT ACTUALLY WORKS. Or rather, I'm happier with the sound now. On the overall, the sound quality has lost a bit of its neutral quality for a more organic sound; the trebles are less well defined while the mids have lost a bit of their shine, imo. But on the other hand the trebles on the earphones were slightly too tinny for my liking in the first place, and the mids still have their strong bodied quality. The soundstage has also improved quite a bit, with instrument separation improving likewise. But the most significant impact would be on the bass response, which was previously quite inaudible but is now quite defined. And blu-tack eartips actually don't really look or feel like crap after being coated with a nice layer of nail polish (coat it with a clear layer first, then whatever you'd like to do with it). The isolation has actually improved, too. I thought the foamies were great at isolating sound, till I tried these on and went deaf to the outside world. (:


 DIY Custom Eartips

http://www.head-fi.org/t/491040/diy-custom-eartips#post_7870434

 

 

A remark about the blu-tack mod:

 

An added advantage over silicon fits: as blu-tack is a 'fluid' material, I found that it perfectly fits your inner ear always, for you just have to push it gently until you get the 'vaccuum' seal.

 

This works over time. This blu-tack mod is not affected by body changes, even if you increase your body fat (i.e.: put on some weight over some months, which, as we know, affects the shape inside your ear and can render the silicon molds unusable).

 

 


Edited by deafmutelame - 11/6/11 at 1:35am
post #14 of 64

Thanks for the info. I wish I did my impressions after I read this because I leaned backwards slightly during the process and felt the pressure change in my ear. I hope that it's not going to have a big effect on my impressions.. I have already shipped the impressions though so hopefully I will get a perfect fit the first time.

post #15 of 64
Thread Starter 
Quote:
Originally Posted by kckc View Post

Thanks for the info. I wish I did my impressions after I read this because I leaned backwards slightly during the process and felt the pressure change in my ear. I hope that it's not going to have a big effect on my impressions.. I have already shipped the impressions though so hopefully I will get a perfect fit the first time.


 

If you felt pressure when you leaned back it's likely that the silicone had already set up. You should be fine. :-)

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