Why Opt for MEMS Speakers for Hearing Aids: Explore 6 Key Advantages

Why Opt for MEMS Speakers for Hearing Aids: Explore 6 Key Advantages

By: Mike Housholder, xMEMS Labs, Inc.

What are MEMS Speakers?

xMEMS has created the world’s first all-silicon MEMS speaker. For over a century, the moving coil speaker, also known as a dynamic drive speaker, has been the primary technology for sound reproduction. The coil speaker is a multi-component mechanical assembly consisting of a voice coil, magnet, chassis/frame, paper/plastic diaphragm/cone, dust cap and spider (suspension). In contrast, xMEMS has consolidated all these functions into a single piece of silicon, creating a monolithic structure to reproduce sound that is inherently more uniform, consistent, reliable, lighter weight, with improved audio resolution and detail vs. the legacy architecture. Our MEMS speakers replace the coil and magnet actuation mechanism with a thin-film piezo layer (a layer in the semiconductor wafer) and we use silicon to replace the paper/plastic diaphragm.

A Closer Look at the Micro Speaker Technology in Modern Hearing Aids

Hearing aids primarily use balanced armature (BA) speakers which are a derivative of the moving coil architecture. Balanced armatures have traditionally been favored in hearing aids due to their small, compact size compared to dynamic drive coil speakers and their efficiency/low power consumption since medical-grade hearing aids typically require at least 18-hour battery life (per day). Also, balanced armatures provide high-quality audio in a narrow bandwidth which is ideal for voice amplification since the human voice only operates within a narrow frequency range. However, the manufacturing of balanced armatures is complex and not automated, relying on manual assembly. This increases part-to-part variability and constrains production capacity.

What Makes MEMS Speakers a Better Fit for Hearing Aids?

xMEMS’ MEMS speakers, specifically our small Cowell device, offer several advantages for hearing aids:

1. Size

xMEMS Cowell, the world’s smallest all-silicon micro speaker designed for True Wireless Stereo (TWS) and hearing aids, is even smaller in total area/size vs. balanced armatures which enables the same deep insertion into the ear canal. Length and width are similar to BA, but Cowell’s height is 1.15mm. This makes it suitable for any hearing aid form factor, including receiver-in-canal (RIC) hearing aids.

Figure 1: Cowell vs. Balanced Armature

2. Wider Bandwidth

Cowell is a full-bandwidth speaker and capable of producing the full human hearing frequency range (20Hz-20kHz). Therefore, it not only can amplify voice, but can also be used for amplifying rich, complex media such as music and movies. This is increasingly important, since new hearing aids are adding Bluetooth for connectivity with our smartphones, TVs, and other media devices. Consumers will demand their hearing aids to amplify full-bandwidth content, not only voice. Also, there are independent studies that suggest extended high frequencies (EHF, above 8kHz) can improve speech intelligibility in the presence of background noise. xMEMS’ MEMS speakers exhibit excellent response beyond 8kHz, surpassing the performance of BAs that typically roll off after 8kHz.

3. Linear Response

xMEMS speakers offer a smooth, linear response without the resonant peaks and valleys often present in many BA devices.

Figure 2: Cowell Frequency Response Plot

4. Reliability

Solid-state MEMS speakers are inherently more reliable and robust compared to BAs. The monolithic silicon structure is more robust to drop/mechanical shock and is IP58 rated for moisture/dust/particulate resistance. xMEMS speakers even survive washer/dryer cycles. This leads to fewer failures at the consumer.

5. Automated, high-volume production

With the new OTC initiative, consumer demand for hearing-assistance devices is expected to increase dramatically. xMEMS high volume manufacturing capacity will be able to support this increased demand where BA suppliers with their manual assembly/manufacturing may struggle to keep up.

6. Non-magnetic

MEMS speakers are non-magnetic, making them lighter and avoiding electromagnetic interference (EMI) with Bluetooth and wireless RF technologies.

Enhancing Listening Comfort for Hearing Aid Wearers

xMEMS solutions offer additional benefits to wearers in terms of comfort. Firstly, the reduced weight (due to the absence of magnets) makes them more comfortable, especially for receiver-in-canal (RIC) hearing aids that sit deep in the ear canal. Secondly, xMEMS speakers incorporate venting features that address two comfort challenges:

Pressurization of The Eardrum

Traditional coil architectures typically are not vented. So, as the speaker diaphragm pushes air to generate sound, it can pressurize the ear canal leading to long-term discomfort in the eardrum. The speaker diaphragm in xMEMS speakers is vented. As it actuates, the vented diaphragm allows any air pressure build-up to escape out the back of the speaker and won’t pressurize the eardrum.

Occlusion Effects

The second comfort challenge with hearing aids is balancing open-fit and closed-fit eartips for managing occlusion effects. xMEMS has a novel active vent solution for this called Skyline. The Skyline DynamicVent provides hearing aid and TWS earbuds the ability of active ambient control to address reduction of occlusion effects, to add more natural passthrough/transparency modes, and to enable dynamic switching between passive isolation and open/spatially aware listening modes. From a performance perspective, Skyline was designed to specifications provided by leading hearing aid OEMs to remove occlusion effects when the vent is fully opened. The addition of a comfort mode (lowest power state, but still slightly open) provides a good balance between power consumption, openness/occlusion effect relief, while still maintaining a good low frequency response for music/media listening.

Embracing the Future of Hearing Aid Technology

Our capacity for high-volume manufacturing and our ability to deliver wider-bandwidth sound reproduction align perfectly with the OTC initiative. As consumer adoption of media-centric, Bluetooth-connected hearing assistance devices continues to rise, we are positioned to meet the increasing demand that BA manufacturers may have difficulty accommodating. And by creating a better hearing experience, we aim to improve the lives of approximately 430 million people worldwide with hearing loss.

Stay tuned to see more innovative solutions powered by xMEMS to create a better hearing experience for those with hearing loss. Request a demo now to explore opportunities to unlock the highest standard of performance, listening comfort, and reliability for your hearing aid design.

About xMEMS

Founded in January 2018, xMEMS Labs is reinventing sound with the world’s first solid-state True MEMS speakers for TWS and other personal audio devices. xMEMS has over 100 granted patents worldwide for its technology. The innovative, monolithic transduction architecture implements both actuation and diaphragm in silicon producing the world’s fastest and most precise micro speakers, eliminating spring and suspension recovery of coil speakers. This results in the most accurate time domain music reproduction, unmatched sound clarity, and an elevated sense of space. Please contact us to learn more.

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