SLM Titanium Expands Options for Hearing Aid Wearers

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Titanium plus selective laser melting (SLM) enables hearing aids that perform better for a wider range of individuals.

"Invisible in canal" (IIC) hearing aids are a popular choice for individuals with hearing loss. More discreet than in the ear (ITE) or behind the ear (BTE) designs, IIC devices are hidden completely (or nearly so) inside the ear canal. Because they are placed so close to the ear drum, IIC devices reduce ambient noise and improve sound quality for wearers.

But IIC hearing aids also come with some critical tradeoffs. Because they must be small enough to fit inside the ear canal, the size of internal components is restricted and IIC devices often lack features such as volume control. At the same time, they may still be too big for some ear canals and variation in the shell for customization is limited.

An IIC hearing aid that could be made with thinner walls may alleviate some of these issues. Hearing aid manufacturer Phonak, a member of the Sonova group, has launched a new line of IIC hearing aids 3D-printed from titanium, called Virto B-Titanium. Titanium is stronger than the acrylic typically used for hearing aids; this strength makes it possible to build a hearing aid with a thinner shell, opening up additional space inside the unit and expanding the range of possible fits so that more patients can wear the devices.

Phonak's parent company Sonova has been involved in the digital manufacturing of custom hearing aids using additive manufacturing since 2001. The process begins with taking silicone impressions of the ear canal, which are scanned using laser technology, and digitally processed to create a hearing aid shell. Once complete, the file is transmitted to 3D printers at the production site (it is also stored in a central database).

In the past, the company has produced hearing aid shells in acrylic via light-curing 3D printing processes. With the Virto B-Titanium line of hearing aids, which are selective laser melted from medical-grade titanium, Phonak has expanded the customization options available for IIC devices with a shell that is 15 times stronger than acrylic. The use of titanium makes it possible for the Virto hearing aids to have shells just 0.5 mm thick, 50 percent thinner than the shells of the acrylic custom hearing aids Sonova produces.

The material and process change has allowed Phonak to improve the performance of IIC hearing aids without increasing the size of the units. Thinner walls mean more available space inside the unit for internal components and design customization. It's possible to install more powerful receivers inside the Virto B-Titanium hearing aids, meaning that patients with a broader range of hearing needs can use the devices. Thinner walls have also enabled the incorporation of a larger vent to reduce occlusion, or the sensation that occurs when sound is trapped inside the ear canal.

In combination with a thinner shell, the Virto B-Titanium hearing aids also feature smaller electronic components, making them as much as 26 percent smaller than previous models. It is currently the smallest custom product Phonak produces, and could potentially be worn by patients with smaller ear canals who were not good candidates for IIC devices in the past.

The Virto B-Titanium line of hearing aids was released to the United States and most countries in Europe earlier this year.