Using LSR in Hearing Components

With Contributing Expertise From: simtec

Liquid Silicone Rubber (LSR) is the ideal material for parts with skin contact that need to meet hygiene, comfort, and biocompatibility requirements. Because it is also flexible and inert, it is the preferred choice for a wide variety of applications.

LSR is designed for use with injection molding, called LIM (Liquid Injection Molding), a technology which allows 3D designs with very thin sections and significant undercuts thus ideal for ear tips and other products that are worn in the ear.

Hearing components require these same characteristics that are available with LSR and LIM. Whether your products improve the listening experience, help bring sound to the lives of the hearing impaired, or are used to protect hearing, LSR is an excellent solution.

Why Is LSR a Good Material for Hearing Components?

LSR’s properties and physical attributes which include the following, make it an ideal choice for hearing components:


LSR has a soft, smooth texture making it pleasant to the touch. Because of its softness and flexibility it will conform to the shape of the ear offering the user a comfortable experience. As LIM technology allows both thick and very thin sections in part design and large undercuts, ear tips are commonly made of LSR. LSR’s low compression set means it will maintain its shape and offer a consistent, comfortable fit, time after time. The wearer doesn’t need to deal with the undue pressure of a hard plastic insert that doesn’t match the shape of their ear. Instead, they get a product that more accurately fits the unique shape of their bodies and is comfortable even for long periods of use.

A soft, smooth texture is a feature that is important for products that are in contact with the skin. LSR offers offer long-term comfort, and will not cause skin reactions or irritation.

Biocompatibility and Hypoallergenic

A product that is biocompatible and hypoallergenic is one that will not have adverse effects on the body. Any item that needs to be in close contact with the body for long periods, such as hearing products, needs to be biocompatible and hypoallergenic. LSR is a common material used to manufacture these types of products because it has these properties.

In addition, LSR is resistant to bacteria and is easy to clean. Products that go into the ear can accumulate ear wax and have the potential for bacterial growth, therefore require cleaning on a regular basis. A material such as LSR can be easily cleaned, and is hygienic, safe and is a great choice.


LSR is perfect for applications where resilience is necessary. LSR has what’s called a low compression set, which means it maintains its elastic properties (“bounces back”), even after prolonged compressive-stress. LSR also stands the test of time, it does not grow brittle or break over time and is resistant to corrosive substances, UV, and vibration.

Many products like ear tips and ear buds are subjected to heavy use, but an LSR component is durable and will withstand repeated use while maintaining its shape and form. Since it holds its shape, users can expect an ear piece that maintains its comfort over time.

Chemical Stability

A contributing factor to LSR’s excellent biocompatibility is its chemical stability. The silicone rubber presents a chemically inert product, so it won’t experience adverse effects from perspiration and other environmental or cleaning substances during use. Products used in the ear should be clean and safe. LSR’s chemical stability will stand up well to routine cleaning and most cleaning products.

Design Flexibility

Another reason many manufacturers turn to LSR is because of how much flexibility it offers in the design stages. The material is very versatile and can take on complex shapes, including those with intricate designs, thin walls, undercuts, and also works well for small parts.

Moreover, LSR is naturally a translucent, milky-white color, so manufacturers can easily add pigments to make it stylish and match various design requirements.

Types of Hearing Components LSR Is Used to Manufacture

LSR is the material of choice for many applications, but hearing products can especially benefit from its properties. Texture, durability, biocompatibility, and comfort are some of the advantages LSR injection molded components offer. Below are a few examples of hearing components that benefit from the use of LSR:

1. Hearing Aid Domes

People use hearing aids to help them overcome a variety of auditory issues, and hearing aids using LSR for the ear components provide several benefits, including:

  • Comfort: For people needing hearing aid products, most must wear the hearing devices all day, therefore a comfortable, conforming shape is paramount for extended wear. The biocompatible nature of LSR is also important for extended wear. Since LSRs are hypoallergenic and biocompatible, users are highly unlikely to experience skin irritation or chemical reaction when in contact with cleaning products and other substances. Since these products are used for long periods, LSR’s soft, smooth texture contributes to its comfort.
  • Design and seal: Part of the reason LSR hearing aids can be so comfortable is the ergonomic design of the product. Lightweight parts with thin membranes and other delicate features are possible due to LSR’s material properties, and the precision attainable with the injection molding process. This gives product designers the ability to create parts that offer a comfortable secure fit and that seal properly in the ear. If the seal is loose, sound can escape causing the hearing aid to whistle. LSR and ergonomic part designs help ensure the dome stays in place so the product will work as designed.
  • Variety of shape and size: LSR’s flexibility extends to shape and size options. It can be used for open and closed versions of hearing aid domes, with the appropriate variation chosen based for different levels of hearing loss. Size and shape will also vary depending on the ear sizes to ensure comfort and stability.

2. Ear Tips

Ear tips sometimes called earbuds make it possible to listen to music with a compact, comfortable sound delivery system. LSR meets many needs for earbud design including:

  • Durability and weather resistance: Ear tips need to be able to stand up to the demands of daily use, especially for those with active lifestyles─ be it indoor work-outs or outdoor activities. Since LSR is resistant to physical and chemical-stress and is easy to clean, it can withstand a variety of conditions such as dirt, water, and compression.
  • Ability to form intricate designs: With the design options for LSR earbuds, intricate parts can be molded, such as those with very thin sections, undercuts, or with unique shapes.
  • Comfort: Whether a user is listening to music or blocking out surrounding noise, ear tips should be comfortable for long-term wear and safe for extended skin contact. LSR earbuds meet both of these needs and can stay in place with a snug fit that conforms to the ear.
  • Variety of colors: SIMTEC Silicone Parts offers a wide variety of color options that allows you to match earbuds to other design components and create an attractive aesthetic appeal.

3. Ear Plugs

Ear plugs offer hearing protection for workers in loud surroundings without getting in the way of their tasks. “Noise-induced hearing loss is one of the most common occupational diseases…and the second most self-reported occupational illness or injury.” Ear plugs are used for hearing protection and worn in a variety of loud environments such as airport runways, race tracks, and machinery operators. LSR meets ear plug design needs, including:

  • Comfort: For people working in loud environments, ear protection products are required personal equipment on the job and worn by workers for their long shifts. A comfortable, conforming shape is important for extended wear and for proper protection. Since these products are used for long periods, LSR’s soft, smooth texture and conforming fit provides a pleasant user experience.
  • Skin contact: The biocompatible nature of LSR is also important for extended wear by all users. Since LSRs are hypoallergenic and biocompatible, users are highly unlikely to experience skin irritation or chemical reaction when in contact with environmental elements or with cleaning products.
  • Durability and weather resistance: Ear plugs need to be able to stand up to the demands of daily use in harsh environments. Since LSR is resistant to physical and chemical stress and is easy to clean, it can withstand a variety of conditions including dirt, water, and compression.

Why Choose SIMTEC to Manufacture Your Hearing Components

For hearing components, there are a lot of factors to consider. Working with SIMTEC, an experienced expert in LSR and manufacturing technologies, ensures you’ll not only get exceptional care and reliability, you’ll also get the best solution to meet your specific production needs. As one of the top silicone rubber injection molding companies in North America, we have a proven track record of providing high-quality parts for many Fortune 100 and leading companies in the medical device, life sciences, automotive, industrial and building technology sectors.

Our advanced technology provides consistency and process stability, so you know you are getting a uniform product each time. For our life science customers requiring hygienically-controlled manufacturing, we offer a Class 8 Clean Room. Our LSR custom injection molding, include single-shot,two-shot, and multi-shot lines, each of which can have unique benefits for the part you need.

To discuss the details of your hearing components,contact a SIMTEC representative today.



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