The fit, surface finish and material of an earmould can affect comfort and sound transmission. In this 2025 interview, Dr. Daniel Bomze (Lithoz GmbH), Dr. Christoph Lauer (CADdent GmbH) and Jurij Belik (OC Otoplastisches Centrum GmbH) discuss ceramic 3D printing for this component of a hearing aid.
For those who are new to this field, the number of parts of hearing aids often depends on the type of hearing aid, but core functional parts often include a microphone, an amplifier/processor, a receiver (speaker), the power source, the shell (housing), and the ear piece also called earmould.
The role of an earmould
Although many people focus on the electronics, the earmould of a hearing aid is, in my opinion, one of the most important parts. Its role goes well beyond just “holding the parts together”, to ensure acoustic performance, comfort & wearability, protection & durability, design & personalization as well as integration with other features.
“It is the part that sits in the wearer’s ear and connects to the actual hearing aid. It bears the weight and should perfectly match the body’s anatomy,” Bomze explains.
“As Daniel said, one function is to carry the weight of the hearing aid, and the other is to direct the sound consistently into the ear, to the eardrum where hearing takes place. That’s important because otherwise the sound from the hearing aid would change each time you place your dome in the ear, like with headphones,” Lauer completes.
According to Jurij Belik, through conventional manufacturing processes, the mould can be manufactured with casting using acrylates or other biocompatible plastics that are poured into molds created from the master model. It may also be milled from pre-formed plastic blocks. After the material is cured, it will require some manual finishing before adjustments for fit or comfort. It’s all a lot of manual labor compared to AM.
With AM that allows for customization, it’s easy to see applications for hearing aids achieved with VAT photopolymerization processes – specifically SLA and DLP. Interestingly, Lauer drew our attention to the fact that they can also be achieved using titanium and ceramics.
“Titanium is still relatively uncommon in this context. It’s been around for a while, but it’s rare. Some well-known companies are now pushing titanium more into the mass market, yet it remains a premium material — not something regular,” Lauer clarifies.
The addition of titanium and ceramics as new 3D printing material additions that could enable 3D printed shells refocuses the debate on a single question: What makes a good earmould?
A closer look at materials that make a good earmould
Although its ideal features can be understood as those of a hearing aid in general, Jurij Belik notes:
“In addition to a good fit, biocompatibility, and ease of cleaning, a hearing aid shell should also be durable, resistant to moisture and chemicals, and aesthetically pleasing. For this reason, the material should be comfortable against the skin and potentially come in various colors or styles to suit individual preferences.”
When comparing plastics, ceramics, and titanium for hearing aid shells, three main criteria emerge: biocompatibility, ease of cleaning, and aesthetics.
Plastics such as silicone and acrylic polymers have long been the standard, but they fall short in some areas. Over time, they can become yellow due to earwax exposure and may trigger allergic reactions in some patients. In the past, those with allergies were sometimes given moulded titanium shells—then an expensive option due to manufacturing challenges—or plastic shells coated with a thin layer of real gold, which is hypoallergenic but also expensive and additionally short-lived. The gold coating needs to be refreshed regularly.
The interviewees highlight biocompatibility, surface finish and cleaning as reasons to consider titanium or ceramics. Their suitability depends on the material grade, processing, finish and individual application; this interview does not establish a universal clinical ranking between these materials.
The experts also describe resistance to wear and cleaning agents as desirable properties. These characteristics should be assessed for the finished earmould and its intended use.
Why consider ceramics for this application?
Speaking of titanium, the material that is increasingly being promoted in Germany, Belik states, “Titanium is not ideal for either the patient or the audiologist. It‘s very hard to grind and to polish it, so if you need to replace a speaker, you have to send it back.”
Describing the properties they seek in ceramic earmoulds, the experts explain that “ceramics stand out not just for their aesthetics, but also for their functional benefits. The shells can be made with completely freeform surfaces—very thin, intricate, and complex—yet still achieve a dense, smooth finish. This smoothness prevents earwax from penetrating the material, unlike polymers, which are slightly porous.
Ceramics can also be polished more easily than titanium and can be glued with adhesives, which is not possible with titanium. Another advantage lies in sound quality: titanium can sometimes produce a slight echo or distortion, whereas ceramics deliver a clearer, undistorted sound for the patient—an important factor in achieving high-quality earmoulds, ”, Bomze and Lauer complete.
From an aesthetics standpoint, materials can be colored or produced in a translucent form to suit patient preferences; an area where ceramics also excel. For example, the LithaBite material enables the production of translucent alumina parts:
“Ceramic is the most natural material for a hearing aid. Unlike titanium, which has high thermal conductivity and quickly matches the outside temperature, ceramic adapts to the body’s temperature, avoiding the discomfort of a ‘cold head.’ Ceramics like alumina-toughened zirconia (ATZ) have a unique advantage: they can be naturally white. In fact, they’re the only material used for hearing aids or earmolds that can remain white over time. Titanium isn’t naturally white, and while acrylic polymers can be made white, they typically lose their brightness within days,” CADdent GmbH expert emphasizes.
This is especially important for patients who specifically request white devices. We learned during our conversation that, depending on the market needs, there’s also potential to produce black alumina-toughened zirconia (ATZ), as black zirconia already exists—offering another appealing color option for those who prefer a discreet, dark look.
ATZ and LCM: Manufacturing ceramic earmoulds
From my understanding, the full production process for the hearing earmoulds takes approximately four days. This includes a few hours for the printing phase with Lithoz’ LCM and then several days for the debinding and sintering (i.e. thermal postprocessing) processes. The timeline is for a single batch, as many earmoulds can be processed simultaneously in one furnace, which helps to reduce production costs and improve efficiency.
“In one furnace run, you can produce tens to hundreds of hearing aid earmolds at the same time. So, when producing in batches, you don’t have to wait for each one individually”, Bomze says, outlining the scalable options.
Let’s do the math:
In the interview, the experts describe a scenario of around 30 earmoulds per print run and four to six runs per day, depending on part height and machine configuration. This is a theoretical printing estimate, not a verified daily output of finished earmoulds. Debinding, sintering, finishing and inspection must also be included in production planning.
When asked if they faced any challenges at the manufacturing level, Lauer said:
“If these had been the first ceramic parts we printed, we would have faced a lot of challenges. But since we had been working with ceramics for two years, the first time we printed this type of geometry, the challenges weren’t immediately obvious. Of course, we did have some initial challenges figuring out where to place the supports—what is important, what isn’t, and where we can replace supports. That was something we learned from Jurij —what is functional and what isn’t.
From a geometry perspective, the earmoulds or earpieces are actually very nice to print because they have spherical, rounded surfaces. One thing that’s difficult to produce in ceramics ceramics is sharp edges, because of mechanical stress accumulation, which we don’t have in this geometry. That makes printing much easier when the design is done correctly.
The only potential concern is that ceramics could break if dropped on a hard surface. In that case, we might suggest redesigning the earpiece, but that’s really the only scenario where the design or 3D printing would be challenging—and only for larger earpieces. That said, many surfaces are functional, so careful planning is essential and there are small features, like tiny canals, that would be impossible to produce without 3D printing. If you tried to mill them, it simply wouldn’t work.”
These examples make ceramics a route worth examining for customised earmoulds. They do not, by themselves, demonstrate clinical superiority over every polymer or titanium alternative. The clinical follow-up of ceramic implants discussed elsewhere concerns a different application and cannot be used as evidence of hearing-aid performance.
Looking ahead, it would be interesting to explore which other components of hearing aids could be 3D printed and brought to scale.
So, where does the opportunity lie?
Population ageing is one factor relevant to the future demand for hearing devices. A U.S. Census Bureau report published in 2014, using the 2012 population projections, estimated roughly 80 million people aged 65 or over in 2040, compared with about 40 million in 2010. This historical projection is not a forecast of ceramic earmould sales.
Discussing CADdent’s activities, Lauer identifies Germany and Switzerland as existing markets and Austria as a possible extension. Reimbursement and regulatory requirements need to be checked in each country; geographical proximity does not establish equivalent rules or coverage for a premium ceramic earmould.
While there’s potential for expansion, he noted that the market is likely limited to Western countries because it is a high-end, luxury product. Typical target markets would include the European Union, the United States, Canada, and affluent customers in other regions. He added that the German market is generally considered the lead market for acoustics.
Editor’s notes
For this traditional catch-up, Daniel Bomze, Director of Medical Solutions at ceramic 3D printing company Lithoz invited to our virtual table, experts from CADdent® GmbH and OC Otoplastisches Centrum GmbH.
With strong roots in dental technology, CADdent specializes in manufacturing dental products using advanced technologies. Their services extend beyond dental technology to include rapid prototyping for various industries, such as electrical engineering, jewelry, aerospace, and other healthcare applications.
OC Otoplastisches Centrum GmbH is a Swiss company that manufactures and sells high-quality audiology products. Their offerings include a range of items like hearing protection, ear molds for hearing aids, and in-ear monitors. They operate a specialized laboratory where they produce custom-made earmoulds to meet demanding specifications. Their products are sold exclusively through specialist retailers.
Lastly, if you’re not familiar with Lithoz’s Lithography-based Ceramic Manufacturing (LCM) process, please note that in this process, ceramic particles are dispersed in a photosensitive resin. This dispersion is thereafter solidified by a light layer-by-layer approach to form a part. Then the part undergoes a sintering process to develop its ceramic properties and can be used for its final purpose.
Disclaimer: This content has been created in collaboration with Lithoz. Insights from Dr. Daniel Bomze (Lithoz GmbH), Dr. Christoph Lauer (CADdent GmbH), and Jurij Belik (OC Otoplastisches Centrum GmbH) have been edited for brevity and clarity.
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