IIC Hearing Aids and Ear Impressions


As of recently, there is a “new” style of hearing aids in the marketplace: the IIC, or Invisible-in-the-Canal style of aid.  IIC hearing aids fit even more deeply than the traditional CIC, in the second bend of your ear canal.




For many years, the CIC has been the tiniest, most discreet hearing aid on the market, but the IIC has taken its place.  Manufacturers now have the capability to design smaller chips and shells for them.  The key to a good fit on an IIC device is an ear impression that is long enough, 10-12 mm past the second bend.

Let’s talk about ear impressions for a moment; many people don’t know exactly what to expect with an ear impression, or how it is taken.  First, the hearing healthcare professional will look in your ear canals to make sure there is no debris or wax that could impede proper impression taking technique.  If you have wax or debris or another medical problem that could prevent his or her ability to safely take an impression, you will be referred to a medical doctor.  If everything is normal, he or she will proceed with the impression by placing an otoblock or otodam down inside the ear canal.  The otoblock is a piece of cotton or foam with a long string attached to it.




The depth of the otoblock’s placement depends on the type of hearing aid being made.  For an IIC, the block will be very close to the tympanic membrane, or ear drum.  The professional will look in the ear to insure he has placed the block at the correct depth and also to make sure there are no gaps or holes around the block.  Then he will fill your ear with a silicone solution mixed with a hardening agent that will take a cast or mold of your ear.  It is not typically a painful process, but it can be uncomfortable and make your ear and head feel very full.  You may also experience feelings of pressure and tightness, but a good sealed impression is necessary for a great fit on a hearing aid.  After hardening for 5-10 minutes, your hearing professional will break the seal on the mold and rotate it while pulling it out.  Here is the result, which is sent off to the manufacturer to make your custom fit hearing aid:



Getting back to IIC hearing aids, there are a couple of technical advantages to this style of instrument.  First off, since it fits so deeply, the ear canal and pinna filter the natural spectrum of sound and the listener is able to take advantage of acoustic cues.  Secondly, the microphone placement on the IIC instrument  helps with localization of sounds, i.e. telling from which direction they come.

The IIC hearing aids are only large enough to have one microphone on them, so directional microphones are not an option.  However, some studies (Starkey Laboratories) have shown that the ear’s natural resonance coupled with the deep fit and advantageous microphone placement have had IIC listener’s hearing just as well in noise as someone wearing a BTE hearing aid.




Not all people will be a candidate for this type of hearing aid.  If you produce a lot of wax, or if your canals are small and narrow or you have issues with drainage from the ear, this is probably not the best solution for you.  If you do not have good dexterity, this is probably not a good fit for you either, as you will have to insert and remove it daily and it fits quite deeply in the canal.  If you want something that you can have a lot of control over as far as adjustments and accessories, this is probably not the best solution for you.

If it does sound like something you are interested in, Hearing Revolution offers the IIC in several models:

Please feel free to contact us with any questions about products and fittings. 1-877-426-0687


Until next time,


Dr. Kristin