On a windy hillside near Copenhagen , Denmark , are the headquarters of a company with a simple goal : to make the smallest hearing aids in the world . Widex , one of the globe 's largest hearing aid companies , developed its first model in 1956 . Back then , it came with its own battery pack and had to be strapped to the chest . They 've been gradually shrinking ever since and 3D printing technology has now enabled the slender machines to vanish almost completely into the ear . `` The smallest are less than the size of the tip of a little finger , '' says Soren Westermann , the Widex CEO whose father co-founded the company nearly 60 years ago . Back then , hearing aid technology had just made a great leap forward following the invention of the electric transistor in 1948 . Westermann recalls that when he was born , hearing aids had been hulking , impractical devices `` that you wore on your back . '' But the energy efficiency and relatively small size of the transistor -- which is used to amplify electronic signals -- paved the way for the now familiar `` behind the ear '' style of hearing aid . Since then , the mechanics have become evermore sophisticated , moving from analogue amplification to digital and from behind the ear to right inside it . Widex are now the pioneers of a manufacturing process known as Computer Aided Manufacturing for Individual Shells for Hearing Aids or , less cumbersomely , CAMISHA . The process takes advantage of recently developed 3D printing technology to create staggeringly precise molds of the ear canal . `` First we make the impression of the ear , '' explains Westermann . `` It 's still done the old-fashioned way : impression material ( liquid silicone ) is injected in the ear and as it sets it shows a perfect reproduction of the ear canal . '' But it 's the second stage of production where things get smart . Standing in the Widex lab , Westermann demonstrates how the finely detailed mold is scanned through a 3D scanner taking millions of measurements to create what he calls a `` 3D point-cloud '' representing exactly the inside of a patient 's ear . Then , layer-by-layer , a large 3D printer replicates the precise dimensions of the mold using photo-acrylic gel , a type of liquid plastic . Finally , the tiny mechanical components -- consisting of a microphone , a receiver , a battery , and an almost microscopic computer chip -- are inserted into the plastic shell . `` The detail that we can reproduce is down to a hundredth of a millimeter , '' claims Westermann . The precision and efficiency of the process has resulted in the world 's smallest ever hearing aids . For Westermann , this is a significant development . `` Invisibility is extremely important ... It is so clear that nobody wants to demonstrate or show their hearing loss , '' he explains . But the CAMISHA process offers more than discretion . Unlike previous models , which blocked large parts of the ear with big plastic shells , the so-called Invisible In-Canal ( IIC ) hearing aids allow for more sound to be collected naturally by the shape of the ear , and to flow down the ear canal as it would with unassisted hearing , improving the fidelity and range of sound . The fact that the shell is modeled so exactly on the user 's ear also prevents any noise from leaking out . According to Westermann , this was the cause of irritating `` whistling '' in previous models . `` The sound will leak from near the ear drum and out between the ear piece and the ear canal . It will leak out there and go back to the microphone , then it will feedback and whistle , '' he said . In addition to these technical improvements , the precision of the mold , says Westermann , means that it is substantially more comfortable . Previous manufacturing methods , which Westermann describes as more like a form of manual sculpting , allowed for small discrepancies between the silicone mold and the hearing aid , causing potentially significant discomfort . `` The ear canal is actually extremely sensitive , so the tiniest irregularity may be intolerable , '' he says . `` Now they are perfect every time . We know beforehand that they can fit , we know they are as small as they could possibly be and we know that we can make them exactly the same every time , '' he adds . At least for now , however , the premium sound and comfort comes at a premium price . While you can get a conventional hearing aid for a few hundred dollars , the CAMISHA produced models range from about $ 1,000- $ 3,000 per device . Westermann , as you might expect , says his customers rarely suffer from buyer 's remorse . `` We get a lot of feedback letters , feedback from people who say ' I ca n't imagine why I waited five years to get one of these , ' '' he says . `` People tell us they had forgot the sound of the birds . They were walking in the forest and suddenly heard these birds again and they had n't heard them for 10 years and they had forgot they were still there . `` That makes a lot of difference in your work , to know that you made a difference to somebody else . ''
Danish hearing aid company develops manufacturing process based on 3D printing . The `` CAMISHA '' process allows exact molds of a person 's ear canal to be produced . As a result , the company has produced the world 's smallest , most comfortable hearing aid .