Completely-in-the-Canal Hearing aids, or CICs, are VERY popular, and for good reason. These instruments are tiny! Many people come into the clinic dead-set on CIC instruments, for better or for worse.
CICs are the small class of custom in-the-ear instruments that go into the canal, and if anything is visible, it's just the end of the face plate. Some especially deep CICs, usually referred to as IICs, or Invisible-in-the-Canal instruments, are completely blended in, or have a deep face plate that doesn't show externally.
Who are CICs made for?
CICs were never made exclusively with invisibility in mind. When custom instruments came out, there were people who wanted the custom fit, but found the full shell and half shell instruments to have too much bass or be too powerful. CICs were made for those with a mild loss and who didn't want or need the extra size.
Today, CICs can be nearly as powerful as their full shell and half shell counterparts (many of our CICs have 10-15 dB of gain difference from the max-out position on the larger customs in that line). People who come in for CICs today are not people generally looking for a less powerful solution or for less bass. CIC-oriented clients usually come in because of the size.
CICs, from an audiological perspective, do best on people who come in with a mild-to-moderate flat or reverse sloping loss. Essentially, they must have some degree of bass frequency impairment. If you have no bass frequency impairment or are VERY severe across the board, you are not the best fit for a CIC.
That being said, you may have a high frequency loss and be in a CIC. It may be working perfectly fine for you! Today's technology allows for a lot of wiggle room when it comes to the prescription; however, you cannot ignore the basic acoustic principles of filling the ear canal. Just like an earplug, filling the ear canal with a CIC that is off will still stop up the high-pitched sounds but not the low-pitched ones. This can lead to trouble in background noise, which is often in the low frequencies, and can lead to people feeling like their own voice quality is "in a barrel" or "in a tunnel".
The biggest downside to CIC instruments in comparison to all other types of instruments is the availability of secondary features on the CIC because of the size.
Speakers have become small, microphones have become small and computer chips have become VERY small. Bluetooth transmitters are not yet small. Batteries are only capable of being so small. While computer chips are small, its circuitry is rigid, which can cause it to take up an oblong space inside the instrument. On top of all of this, the speaker and the microphone have to remain a certain distance apart or else they could feedback.
Sound like a lot to engineer? It's especially difficult when you're working with 15-20 mm of space!
Bluetooth is pretty much, as of 2019, unavailable in CIC instruments. Rechargeability is unavailable as well. Windscreens are usually unavailable or at least simplified. Certain microphone patterns, such as backwards-facing microphones, may be unavailable because the CIC has no backwards-facing parts that are external.
At the end of the day, it is between you and you hearing care professional to determine whether a CIC or another type of hearing instrument is the best fit for you. If you are a candidate for a CIC or an RIC and you are leaning towards a CIC because of size alone, ask your Audiologist or Hearing Aid Dispenser about the features of the RIC versus the CIC. Weigh the features and the size against each other. There are certainly jobs that require heavy public speaking, sales or customer service where the size requirement of the instrument may heavily outweigh its features. At the end of the day, the most visible hearing loss is always the one that goes untreated!
(Quick author's note: If I sold anything other than hearing aids, I would probably want a CIC over a RIC for aesthetic, so I get the hype).