Do you mean smallest custom or smallest behind-the-ear device? There are some differences between the styles with regard to reliability and durability. Behind-the-ear products are going to have a bit more durability because they are not subject to as much dirt, debris, moisture, and earwax as custom devices; however, there are more parts involved, so those parts may need more maintenance...
With regard to size, different providers will have varying opinions, depending on what they work with more often and what their patients report, but from my perspective, the smallest custom products that still have great sound include the Phonak Titanium and the Starkey CIC devices (not sure what the product line is - i.e. Muse). Most other manufacturers can't seem to get the device down in size as small as those two). The smallest behind-the-ear device that still offers strong reliability and durability is the Resound Linx 3D device - which also offers direct iPhone streaming and use of a smartphone App. Widex has the Unique Passion series which is smaller than the Resound, but in my opinion, not as durable and without smartphone streaming (Their newest line - the Beyond, does not come in the Passion model).
Make sure you are working with a professional who understands what it is you are looking for and can find a product that will e most appropriate for your hearing needs. Depending on hearing loss degree and configuration, one style might not be appropriate - even if you are looking for "smallest" in size or custom versus behind-the-ear.
Good luck with your search!
The smallest hearing instrument available will vary from person to person depending on your hearing loss and shape of the ear canal. Many manufacturers offer IIC (invisible-in-the-canal) hearing instruments which may be considered the smallest by some people, however depending on the shape and size of your ear canal this instrument may or may not be invisible. For this reason many audiologist and hearing instrument users find the RIC (Reciever-in-the-canal) style hearing instrument to be more invisible in the ear as the pinna (the outer part of the ear) hides most or all of the hearing instrument behind it. If cosmetics are a concern for you make sure to let the audiologist your working with know that. He or she will be able to determine the best instrument for you taking into account your hearing loss as well as the shape and size of your ear canal.
The smallest hearing instrument on the market is Starkey IIC invisible hearing instrument. It offers wonderful technology and even has Bluetooth. Fitting deep in your ear comfortably and providing excellent sound quality. Another small option is the Muse RIC device which when placed behind the ear turns out to be hidden and almost completely invisible. There is so many wonderful options to choose from that hearing instruments don't have to be seen any longer.
ReSound LiNX 3D is the best option. Receiver in the Canal option means it is primarily outside the ear, meaning less moisture and wax get in other than the receiver, which can be replaced in the clinic in minutes. It still uses a 312 battery, so you get close to a week without changing it. Most smaller options require a 10 battery which needs to be changed every 3 days. Some custom hearing aids could be considered smaller as they are fully inside, but because of that they are more likely to wear out and have issues.
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