The smallest technology for powerful hearing experiences

They are often only a few centimeters in size and yet make a big difference to their wearers – hearing devices. Just a few years ago, many models were clearly visible. For those affected, this meant not only that they were often uncomfortable to wear, but also that their disability was exposed. Today, the technology is not only more advanced – above all, it is smaller. Modern hearing aids are almost invisible to outsiders and their performance is better than that of older models.  

Not all hearing aids are the same 

As in many other areas, different technologies and designs have become established for hearing aids. The individual needs of the user, as well as availability and price, determine which aid is suitable for which person. 

An overview of the most common assistive devices for hearing loss:  

• Behind-the-ear (BTE) devices are among the oldest and most common forms of modern hearing aids. A housing located behind the ear amplifies the sound received and transmits it directly into the ear through a tube, the so-called sound channel or sound tube. The relatively large casing makes it possible to install powerful batteries. At the same time, wearing the casing behind the ear means that the devices are somewhat more conspicuous than other solutions. Unpleasant acoustic feedback can also occur if they are not used optimally. Earlier devices were often not suitable for people who wear glasses, as the external housing blocked the space for the temple of the glasses. Thanks to their small size, modern devices usually leave enough space for glasses & co.

• Receiver-in-canal (RIC) devices look like behind-the-ear devices. However, instead of a sound tube, they use an electrical sound transducer that is inserted into the ear canal in a similar way to the sound tube. While the design of these devices makes them less conspicuous than behind-the-ear devices and can provide a more natural sound, they require more regular cleaning and the risk of damage requiring repair is somewhat higher.

• In-the-ear (ITE) devices are custom-made hearing aids that are worn completely in the ear. They are significantly smaller and less conspicuous than BTE or RIC and are also suitable for spectacle wearers and athletes. Earlier models suffered from low battery power and were only sufficient for mild to moderate hearing impairments. Thanks to advances in microtechnology, the devices are now just as powerful as devices fitted outside the ear and can be used for almost all degrees of hearing loss. However, the cost of in-the-ear devices can be somewhat higher than that of comparable behind-the-ear devices.

• Cochlear implants are hearing prostheses consisting of an external and an implanted part. The external part, consisting of a microphone, processor, battery and coil, captures received acoustic signals, converts them and sends them to the implanted part, which stimulates the auditory nerves with the signals. The associated hearing experience for wearers is very different from the hearing experience of people with normal hearing. Accordingly, intensive training is required after the operation in order to be able to classify the signals received. Nevertheless, cochlear implants offer the greatest possible improvement for people with hearing loss, so that even almost completely deaf people can have a certain hearing experience. 

Advantages of modern microtechnology 

All the hearing aids and implants mentioned have been around for many years. As the German Medical Technology Association states on its (German) website, the first electronic hearing aid was created around 1901 with the "Acoustikon" by American electrical engineer Miller Reese Huntington. It weighed an impressive 12 kilograms at the time. Since then, the technology has continued to improve and has shrunk to a size of just a few centimeters and a weight of just a few grams. A relief for those affected in the truest sense of the word.  

But even today, companies are still working on developing ever smaller components and materials for hearing aids and enabling users to participate in life as fully as possible.  

The Swiss company Renata SA, for example, has developed special zinc-air batteries for hearing aids. They not only increase the performance of the devices, but also improve their running power. "These reliable and powerful batteries are the ideal choice for analog and digital hearing aids and deliver a constant current for optimal sound quality," explains the company. 

Stansomatic A/S from Denmark manufactures matching battery springs, switches, shields and other stamped and deep-drawn parts. The high-precision stamping method allows complex parts down to a size of 0.05 mm to be manufactured and installed.  

Evonik is also developing microtechnology for hearing aids with TROGAMID®. The special microcrystalline plastic is particularly resistant to chemicals, stress cracks, UV radiation, bodily fluids and medications, thus ensuring a long service life for the individual components.  

The SEMECO project intends to break completely new ground. Launched in May 2023, the "Secure Medical Microsystems and Communications" project with partners from the Technical University of Dresden aims to break the innovation backlog in the medical technology sector and, among other things, develop a communication implant that is designed to surpass the functionality of today's hearing aids.  

It is clear that the development of hearing aids is far from over. The importance of past, current and future developments for those affected is also made clear in the article "Louder is not always better: assistive devices for people with hearing disabilities" at the REHACARE trade fair.