Custom in-ear monitors fit guide

So, you just received your custom in-ear monitors (CIEMs) and put them in; ouch, they just don’t feel right.  A sinking feeling goes through you as thoughts of sending your brand new custom back for a refit fill your mind.  Do you really need a refit, or will you get used to the fit?  This custom in-ear monitors fit guide will help you with a better understanding of what makes a good fit.

For first time CIEM owners, it is important to figure out proper insertion technique, make sure the shell is lubricated, and assessing your ears tolerance for a full shelled CIEM.

There are different techniques for inserting and removing acrylic and silicone shells.  Not all CIEM shells are finished the same as some have a slick coating on them that acts like a lubricant while others are dry and not easy to insert.  In fact, most of the CIEMs I have started out dry and adding ear lubricant the first 5-10 insertions helped dramatically with both fit and seal.  Some CIEMs come with a lubricant while others don’t.  If you don’t have lubricant, saliva will work, but make sure you don’t get any lubricant into the sound tubes.  Over time, your cerumen (ear wax) will lubricate the shell and make insertion easier. Failure to use lubricant can result in ear irritation, a difficult time inserting the CIEM, and a poor seal.

If you decide you want to lubricate the shell and have applied the lubricant, the next step in insertion.  For me, I insert and remove acrylic and silicone shells differently.  Starting with acrylic, it is a twist in, twist out motion.  The canal portion of the shell should be behind your ear canal, closer to the back of your head.  Once the canal portion of the shell is inserted into the ear, rotate the canal portion up to fit into place.  With acrylic shells, I usually use the cable for assistance in the twisting.

insert & remove

Removal is similar, but the opposite rotation direction. Pulling the CIEM out without the twist shouldn’t be possible, or if it is, it will most likely be painful. I do admit I usually start twisting the shells out by pushing on the top of the shell connector of the cable. Insertion and removal takes half a second and is much quicker than inserting/removing a universal IEM.

Silicone is similar, but for me, there is more of a twist and push than just the twist of acrylic. The reason for this is the silicone shells are softer and will bend during insertion, and I don’t want to use the cable during insertion or removal. Speaking of removal, I make sure to grab the shell and not apply pressure on the cable as I don’t want to damage the shell. Silicone typically also needs lubricant.

How do you know if you have a good fit? The things you want to check include the seal, comfort, and sound.

Seal: CIEMs offer a good deal of isolation, and you should be experience a relatively significant amount of isolation when the CIEM is inserted. Mouth movements shouldn’t break the seal, and with some CIEMs I need to break the seal to remove pressure developed during insertion. If you have a vacuum when you insert the CIEM, you know the seal is good. If you can break the seal when chewing gum, you could probably use a bit tighter fit.

comfort: While the sound is very dependent on the fit, in my experience, comfort also affects the sound. I have had CIEMs that were too tight and hurt, and when I shaved them down with a bench polisher, the sound improved. There are typically three areas that can cause issues: the canal, the upper concha area, and the base of the canal.

Custom In-Ear Monitor (CIEM) Fit Issues

A perfect fit can often be achieved by making a great impression, but there are time when even a great impression doesn’t result in a perfect fit, with some minor fit issues.  And, another thing to take into consideration is that your ear canal sizes can change depending on several factors, with the most common ones being weight change (and water retention/dehydration), being sick, such as having a head cold, and irritation.

Typically there is a set time for sending a CIEM back for a refit, so it is important to address any issues as quickly as possible.  If you have any obvious severe fit issues, you should contact the manufacturer after trying a few steps listed below.  If you have minor fit issues, your ears may or may not adjust to the new shell.  Common fit issues include the canals being too large, small, long, or short, the upper concha area not fitting right, or a poor sound tube angle.  Let’s look at some of the fit issues and how you can deal with them.

A) Canals:
Canal too large: This can cause either pain or discomfort ranging from immediately to after a good deal of time such as an hour.  If it hurts right away, chances are you will need a refit.  If it hurts after some time, your ears may adjust and the pain.  Discomfort is something that will go away for many people, but not always.

Canal too long: This will feel like there is something poking the inside of your ear that shouldn’t be poking, or could even prevent the shell from seating properly inside your ears.

Canal too small/short: This will lead to a lack of bass and possibly tonal issues.  An easy way to check is to push the shells in your ears deeper with the palms of your hands while turning shells a bit to constrict the size of your ear canal.  If the sound improves and you hear more bass, the canal is too small.

Canal not at the right angle: If the sound tubes are not at the correct angle, this will affect the sound ranging from a bit to a lot.  A tell tail sign of this is the sound is muffled or lacks a part of the frequency spectrum in one or both ears.  To check for this, look up and down and move the shell around in your ear to see if the sound gets better.  Try to identify when they sound best and contact the manufacturer.  If you can get another set of deep impressions, you may be able to see where the issue is located.  The more you can communicate to the manufacturer, the better their ability to fix the issue.

B) Cymba (AKA Upper Concha bowl):
Cymba area sore: In my experience, this doesn’t go away over time and the area needs to be shaved down, which generally requires the CIEM to be sent back.  It is possible to fix minor issues by using sandpaper.

C) Base of the canal:
If the base of the canal isn’t properly aligned with the angle of the canal, the fit will suffer as one part of the shell will either not sit at the correct angle, causing pain, or the canal will not create a proper seal.

Other issues:
Sound tube angle: sometimes the sound tube angle is oriented at a weird angle, or it doesn’t fit the natural curve of your ear canal.  This can lead to sound issues and possible issues when inserting/removing a CIEM.

When fit properly, Custom IEMs offer extreme comfort and exceptional sound. When they don’t fit properly, the sound and comfort suffer, and the chances of you using and enjoying them decreases. If there are issues with your CIEM, get them fixed ASAP as the short term hassle will be worth the long term benefits.

Fixing acrylic CIEM shells without sending them back:

CIEMs usually have a refit period that typically ranges from 30 to 90 days, and if you have fit issues within this time, it is recommended to work with the manufacturer for a free refit.  If you have had your CIEMs for quite a while and have issues due to the canals being too small or losing a seal during movement/singing, look into Comply Custom Wraps.

If your CIEMs were manufactured in another country, or if you are a hands on type of person, you have options to fix a poor fit. You can find a local audiologist/lab to make the adjustments for you or you can fix them yourself. There are some audiologists that can fix your issues in their office, but many will require the work to be done in a lab, and often it is difficult to find a local lab or get the lab to work directly with you. Audiologists should have experience fixing fit issues with hearing aids, so a similar procedure should occur, but there are differences between a hearing aid and a CIEM. It is best to work directly with the person doing the work and be cognizant of their experience level and what they plan on doing before they do it. Your best bet is to communicate with the CIEM manufacturer to ensure they will still do a refit if the local audiologist isn’t able to fix your issues first.

If you are a hands-on person, you can get high grit sand paper, a bench grinder, and some plastic polish to reduce areas that are too tight and get a better fit. I have used this method, and while the fit became perfect (and the sound improved), the finish wasn’t quite as good as the original if examined closely. If the shell is too small, it is possible to build it up with clear acrylic nail polish. I recommend organic nail polish as the regular nail polish I initially used irritated my ears. Make sure to clean the shell well before applying nail polish and apply many thin coats, making sure the nail polish dries completely between applications. This is a time consuming process, but if you can get a better fit and save the time and money of shipping a CIEM back, it may just be worth it. Another method is Blu Tack, which can be used to fix large discrepancies.

Written by average_joe


  1. Hi Joe, just got my first acrylic CIEM (JH13). When I twist and push them in my ears a vacuum is achieved. Then they give just a bit, but I don’t think it’s enough to break the seal. I hear like 5% outside noise, but the bass is not reduced to my ears. Is this normal?


    • If the sound is good and there isn’t pressure in your ears, the fit is fine. CIEMs isolate better than regular IEMs, and filling the ear can be a different experience for some. How is the treble? If you move the CIEM around a bit more, or even back it out a bit, do you get a better result?

      • Treble is unaffected, and I’ve learnt that with time the acrylic shell gets easier to insert bcos of the extra lubrication from the ear. The fit is perfect, so to speak. Thanks for your time.

  2. Hi, I feel like my ciem is slightly loose and I want to apply nail polish but I’m not sure where to apply it. Also if I do it badly will I be able to remove it without damaging the original ciem? Thanks

    • Sorry for the delayed reply. Applying nail polish is for fixing smaller issues and will be difficult to apply enough to fix larger issues. If the issues is larger and you are out of your refit, you may still want to contact the manufacturer and let them know you didn’t realize they were loose and see what they say. If they are in the refit period, the best is to send them in.

      Something I have thought about but not done is contacting a local audiologist and see if they can help by taking another set of impressions and comparing with the shell, adding a bit of acrylic where necessary. Risky in a way since you never know if the audiologist is really good. You should find one that has their own lab, or goes to a lab themselves.

      Back to the original question…typically the nail polish needs to be applied on the canal. Move the CIEM around in your ear until you figure out how to press to get a good seal, and then apply in that area. Or, you can try using something like the Comply Custom Wraps to test the location of the issue.

      Let me know if you have any other questions and if you are able to fix the fit issue.



  3. How do you use Blutack?

    I meant I did used it but it doesn’t dry up and keeps changing its contact areas, everytime u put it in.

    • Sorry for the delayed response. Blu tack will adjust, but using less is best. It is not designed to fill huge gaps, but decent sized issues, and in such usage, should work. Make sure the CIEM is clean and dry, put a relatively thin layer over the appropriate area and then it should work. Comply foam strips may be better for most applications.

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