Getting Ear Impressions

If you are going for custom-fit IEMs then talk to multiple audiologists, as well as see whether there are any other companies that are recommended by IEM makers in your region who have done this before. Typically the process is no different from those getting hearing aids so any decent audiologist can do it, but I went out of my way to find one who has worked with audio companies and also has a 3D scanner on site for reasons we'll get to shortly. The cost of getting ear impressions varies heavily on where you live and who you go to and it cost me £60 per set including the 3D scans (£45 without 3D scans).


I visited the ear impressions place after making an appointment first and this was in January 2022, when the UK still had COVID restrictions. I went through the entire process first and then my partner decided to get her ear impressions taken too, which allowed me to get some photos and the video seen above. The audiologist first would inspect your ear concha and canals to see if there is any blockage or too much ear wax that could get in the way of good impressions. If there is any detritus or excessive cerumen (ear wax) then it needs to be first removed. Keep in mind that ear wax in itself is not a bad thing so you should not go to your appointment having removed all wax yourself, and certainly do not use q-tips to do so.

The next step involves you deciding how you would use the CIEMs. Is this going to be more a sitting down and relaxing situation with your mouth/jaw typically closed? Would it be more for stage performances perhaps where you would move around and talk/sing? Even if you are somewhere in the middle where you are the type to really get into the music and lip sync even, it's best to have a bite block that you sink your teeth into and thus keep your jaw fixed in position while the impressions are being taken. In my case I opted for no bite block and impressions taken with my mouth closed that would be ever-so-slightly different from when your mouth is open as it affects the shape of the concha. Go ahead and feel your inner ears at the bottom while you open and close your mouth to know what I mean!

Once your ears are deemed ready to go, then get comfortable as the audiologist would insert a physical dead end piece deep into the ear canal with a string attached to it to allow for it to be pulled out. This would prevent the impression forming material to go past the block and adhere to it so that you can easily pull the whole thing out. This step can be uncomfortable but it's only a matter of a few seconds. Now you will feel as if you are under water or even in an air plane with low pressure so remain calm and wait for something cold and gooey to filled into the ears from inside out. Here I recommend getting the audiologist to go at least past the first bend of your ear canal if not further. There are multiple versions of the mold forming material which also can be two separate entities inserted and mixed in the ear cavity or a single one as in my case with the Otoform Xpand, that is a pressure-forming impression material. Think of it like fancy putty that hardens over 5-10 min to make for a salmon-colored 20 Shore A hardness mold. The same is repeated for the other ear and you are done—the entire process should take under 30 minutes.


Seen above are my ear impressions that are pulled out and then cut off at the end to remove the block pieces. This is another reason to go deeper than you would think necessary, but the end result is a set of physical molds that can be sent out to your CIEM manufacturer to be used as resin molds to make shells the IEM drivers and any other components fit into. They also make for excellent ear plugs too in case you end up going to a loud concert, are at a fireworks show, or even work in a loud environment. But don't use them for a long period of time as they do block airflow to the ears completely if the ear impressions were taken accurately, and it's also good to use them for future references to check whether they still fit your ears in case you want to get CIEMs in the future. It's recommended to get new impressions taken if the previous ones were done so ~4-5 years ago, if not even under that. Some impressions also slowly disintegrate over time or are softer than the ones I have so they require further care for transportation back and forth.


This is where 3D scans come into the picture. You may not feel comfortable shipping the physical impressions over for whatever reason and COVID regulations at the time also meant some countries simply were not accepting parcels from other countries. LETSHUOER is based in China, which still is following a zero COVID policy as of October 2022, and the LETSHUOER representative and I both agreed to go with 3D scans to prevent logistics issues as much as possible. The company I had got my impressions taken at also have a fantastic 3D scanner customized for ear impressions so, after another 20 minutes from when the ear impressions were ready, I had STL files in my email inbox ready to go. A quick check against the physical pieces and I was happy enough to send them over to LETSHUOER who then confirmed there is plenty of room to fit the EJ07M's acoustic engine inside. That's right—after all this effort and money spent there is still the possibility that some IEM designs simply can't physically fit into your specific CIEM molds. It's best to take a photo of your ears and send them to the IEM company first if you suspect you have smaller ear concha/canals.

There is a couple of other reasons to go with 3D scans. Some audiologists offer in-ear scanning that does away with the physical impressions completely, and this is a far more accurate and quicker method to obtain your digital ear impressions if paired with both a good scanner and an experienced person undertaking the process. Needless to say, it's also more comfortable than the route I went with. This is far less common, but hopefully will become the norm sooner rather than later. Another reason is that a few IEM makers have gone away from using molds and resin fills to simply 3D printing the CIEM shells in either resin or even metal in a few rare cases. This would also benefit greatly from having STL files sent over for them thus.