Additive manufacturing of hearing aid requiring anatomical precision

Earlens, a innovative hearing aid maker, used additive manufacturing to make anatomical precision hearing aid a possibility

Earlens Corporation, an innovative light-driven hearing technology company, leveraged additive manufacturing process to help manufacturer its custom-built hearing aids. Earlens’ product converted sound to light using a special light-sensitive lens. This lens made direct contact with a patient’s eardrum and activated the patient’s hearing system. Since the hearing aid’s lens needs to make contact with a patient’s eardrum, each product must be custom built with anatomical precision.

Naturally, the need for anatomical precision came with the challenge of scalability. The need to custom built each hearing aid meant that it was impossible to mass produce the hearing aids in the traditional assembly line setting. Also, finding economic ways to map biometric features of a prospective patient and then prototype the hearing aid provided additional challenges.

To address the challenged, Earlens partnered with an additive manufacturing solution provider called Carbon. Carbon provided hardware and software technology that not only provided additive manufacturing that enabled production of hearing aid molds with anatomical precision, but also provided adaptive manufacturing that made quick changes possible. In addition, Carbon integrated software of additive manufacturing with the hardware, allowing easy changes and modifications to the manufacturing process.

Why is additive manufacturing important to Earlens’ product development?

Earlens’ innovative sound-to-light technology created a better hearing aid, because Earlens’ product can eliminate the whistling noise traditional hearing aid had. However, the precise and customized product attribute made commercialization of the product a challenge. Additive manufacturing enable the company to rapidly manufacture high precision hearing aid molds and to manufacturer a large number of individual, idiosyncratic molds. Both of the speed and flexibility helped to make Earlens’ hearing aid a commercial possibility.

In contrast to additive manufacturing, traditional manufacturing processes such as injection molding and casting posed two challenges. First, traditional manufacturing processes were too inflexible and time consuming. Elaborate setup were required to manufacture only one customized hearing aid mold. Second, traditional manufacturing processes had challenges in meeting specific geometric and physical attributes of the product.

Carbon, Earlens’ manufacturing partner, had an additive manufacturing solution that address the precision requirement for hearing aids, but also provided flexibility as the manufacturing process was guided by software design, allowing the production process to seamlessly change between different fittings of hearing aids.

What is the organization doing to address this issue in the short term and medium term?

Earlens’ is currently using additive and adaptive manufacturing to produce the mold for hearing aids with high levels of accuracy and precise specifications. Over the medium term, Earlens’ may use additive and adaptive manufacturing to directly produce their hearing aid, thereby reducing cost and improving speed.

Also, according to, a hearing aid product review site, physical comfort of Earlens’ hearing aid only had an approval of 41%, the lowest among ten other attributes (such as hearing improvement, benefit on the phone, clear and natural sound, etc). Additive manufacturing may be the solution to Earlens’ problem – precision manufacturing, along with software driven, technology enabled biometric (ear shape) mapping tools may allow Earlens produce the items that offers patients with better comfort.

What other steps do you recommend the organization’s management take to address this issue in the short and medium term?

I would recommend the management of Earlens’ to improve connectivity and reduce customer experience friction between diagnosis, fitting, and use. The goal should be making the three elements (diagnosis, fitting, and use) an easy, integrated experience. Ideally, Earlens should acquire mapping and analytics capability, through in-house R&D, acquisition, or partnership. A potential idea is to have Earlens mail a wearable diagnostic toolkit to a prospective user; the diagnostic toolkit  would test hearing capability, map biometrics of the patient, and provide immediate cost estimate, manufacturing timeline, and potential in-patient consultation for hearing aid installation.


In the context of this organization, what are one or two important open questions related to this issue that you are unsure about that merit comments from your classmates?

First, I’m not sure whether rapid diagnosis, real time cost estimate, and immediate consultation have much value add to a prospective patient. I think functionality, product education, and marketing will be more important for the end users.

Second, it is unsure to me whether additive manufacturing can manufacture implant hearing aid with desired surface attributes, texture, and strength requirement.



  1. “Earlens Light-Driven Hearing Aid | Product Info, Reviews, Prices, Videos, And More”. 2018. Hearingtracker.Com.
  2. “Earlens | Earlens Device”. 2018. Earlens.Com.
  3. “Adaptive Manufacturing: Earlens Case Study – Carbon”. 2018. Carbon.


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Student comments on Additive manufacturing of hearing aid requiring anatomical precision

  1. I found this piece to be really thought-provoking. We hear a lot of news about machine learning in medicine but not as much about additive manufacturing. I think your questions are really important- and my gut instinct would say diagnosis and “speed of printing” would be important for the consumer as they seek to get the issue sorted. You mention that customisation is why this hearing aid is to particular and only possible through 3D printing, this leads me to wonder what else could they customise on the hearing aid, such as size, flexibility, waterproof capabilities etc?

  2. Very interesting piece highlighting a use of technology. Thanks for sharing, and I’m appreciative of your skepticism. It sounds like this might be a case of a company being product-focused and not customer-focused.
    One piece of data that I think we could add to this analysis is how many hearing aids does the average customer go through in their life?
    If we knew in how many instances one might experience the frustration of a long lead time, we might be able to better assess the true value.

  3. This is an extremely interesting article — really enjoyed reading about this.

    One thing that you suggest in your piece is to have Earlens mail a wearable diagnostic toolkit to a prospective user. I would argue that this may not be possible for the average hearing aid consumer. From my clinical experience, typically the patients who require hearing aids tend to be elderly and oftentimes have difficulty navigating technology. Consequently, it could be difficult for them to figure out how to use a mailable diagnostic toolkit with features that could test hearing capability, map biometrics, etc.

    The second thing I would say based on my clinical experience is that hearing aids are extremely expensive, and this represents one of the greatest pain points for patients. This article mentions that Earlens could reduce the cost of its hearing aid by using additive manufacturing to directly produce the hearing aid, which I think is crucial to its value proposition. I would expect that consumers probably don’t care that their hearing aids (or the mold used to produce their hearing aids) are produced by additive manufacturing — but they certainly would care if their hearing aids were cheaper.

  4. Thank you for this interesting piece! One of my closest friends uses a hearing aid, and is often prone to losing it. In my opinion, making hearing aids less expensive to purchase will definitely be a very useful value proposition to most customers. I also agree with your recommendation that Earlens consider other distribution mechanisms like direct mail. This ties directly in with the customization options offered by Earlens, and once a customer’s data is stored on those database, the customer can order a replacement online and get it at his/her home without having to go to the store/clinic. However, I am concerned that the products may not be mechanically robust enough to be sent via postal mail, without having to be carefully packaged in a potentially cost-restrictive way.

    I believe that immediate consultation may have a huge impact on customer purchase decisions, and more importantly, customer retention. Since users can be easily trained to install their own hearing aids, this will not require Earlens to bear a huge cost, but will definitely improve the perceived experience of customers who do need service and help with installation.

    Also, additive manufacturing definitely has a long way to go, but given the rapidly improving trajectory it is on, I believe that the mechanical and design attributes can definitely be improved. Given that this seems to be a solution that can benefit from scaling effects, I definitely see the product quality improve with burgeoning growth.

    Another recommendation I have for Earlens is to offer customizable design options to make hearing aids fashionable and trendy, and make wearing them an enjoyable experience.

  5. Thank you for this lovely article! Such an insightful use of additive manufacturing and 3D printing for medical purposes and to provide added value, rather than just making a process more efficient, this actually makes a product possible. I think additive manufacturing have reached the point of producing desired surface attributes, texture, and strength requirement. An example to look at would be dentistry that are utilizing additive manufacturing for denture fabrication and maxillofacial prothesis.

    On the diagnostic toolkits, in dentistry they are using biometric scanning, but the ear is a much more complex organ and it would be interesting to see how technology advances in that space. At the moment I agree with you that patients may be less likely to value that service.

  6. Super interesting article! I think this a very interesting product – if they can scale it, it would definitely be a hit. Thinking about the elderly crowd, there is significant opportunity to tie something like this to Medicare. I see your point on the texture of 3D printing now, but I have to assume that as it continues to innovate, there will soon be the ability to print on many more surface types. Will certainly be keeping an eye out for this!

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