xMEMS introduced the Skyline DynamicVent in 2023 to solve many of the unaddressed consumer experience issues with TWS earbuds. Skyline is a novel, but straightforward extension of xMEMS' innovative MEMS speaker platform that enables a system DSP to actively control the venting and leakage of ambient air into the earbud. How can a MEMS acoustic vent bring the next level of innovation to true wireless stereo (TWS) earbuds? First, we need to examine the current state of the wireless earbud market to understand how this MEMS vent can enable future earbuds to dynamically adapt to multiple environments and situations and improve the consumer experience.
xMEMS Skyline
Source: xMEMS Labs
By now, most of us have owned multiple pairs of wireless earbuds since they gained popularity in the mid 2010s. For most of that time, earbud design fell into one of two camps – open-fit or closed-fit – both of which come with their own strengths and weaknesses. As such, I often switch between open-fit earbuds that rest in the outer ear, like Apple's AirPods or Bose's new Ultra Open Earbuds, and closed-fit types with silicone tips that go deeper into the ear canal to create a seal, like the AirPods Pro.
Open-fit earbuds
Source: xMEMS Labs
Closed-fit (occluded) earbuds
Source: xMEMS Labs
But why do I need two pairs of earbuds? Why is each type ideal for certain situations, but not for others? The culprit: Occlusion Effects.
Building A Better Earbud
Closed-fit earbuds are great for isolation because they physically block sound from entering or exiting the ear canal, which is known as occlusion. Either with or without additional Active Noise Cancelling (ANC) software, this isolation allows me to better enjoy my music or maintain focus in noisy environments. But blocking the ear canal also produces internal resonance and amplification of sounds my body makes such as footsteps, speech or chewing, also known as occlusion effects which can be both distracting and annoying and detract from a comfortable user experience. Anyone who's gone for a jog with deep earbuds or wears closed-fit hearing aids will be very familiar with this experience.
With open-fit earbuds, air can move in and out freely from the ear, and this "venting" of my body's internal sounds removes occlusion effects, enabling a more comfortable user experience. By eliminating the occlusion of the ear, I also have improved awareness of my surroundings. However, this venting comes at the expense of audio quality. An open, non-occluded ear results in a loss of low frequency energy and reduced bass effect, requiring larger, heavier speaker drivers to recover some of the lost energy. Also, ingress of external noise from these open, leaky earbuds takes away from maximum music enjoyment. Open earbuds typically cannot effectively employ ANC, either.
To mitigate the differences and trade-offs between open and closed-fit earbuds and deliver to consumers a truly no-compromise solution, manufacturers have experimented for years with active vents or valves in earbuds that can open and close to provide the best attributes of both earbud types in a single device.
Early attempts by consumer brands with electromechanical, non-solid-state vents have resulted in deployments into small volume hearing aid products, but were not reliable enough for broad, high-volume market adoption. Complications such as a short product lifespan of roughly 6 months due to vulnerability to moisture and particles, and an audible clicking sound during open/close state changes dissuaded further adoption.
We found that delivering a best-of-both-worlds earbud design requires a more fundamental innovation that leverages the latest advances in MEMS (Micro-Electro-Mechanical Systems). Using the world's first solid-state MEMS DynamicVent, called Skyline, manufacturers can now develop true wireless stereo (TWS) earbuds, hearing aids and sleep buds that offer all the benefits of closed-fit and open-fit types without any compromise.
Solid-State MEMS Delivers the Best of Both Worlds Performance and Quality
Manufacturers integrating Skyline enable earbuds that dynamically switch between open-fit and close-fit characteristics in real time. In closed mode, Skyline can attenuate outside noise by as much as 30dB without DSP and power-hungry ANC. When combined with ANC, noise suppression gets even better. This superior isolation delivers the best overall music listening experience and improved focus for work and study.
Paired with DSP noise detection, Skyline DynamicVent enables earbuds to dynamically switch between open-fit and close-fit characteristics
Source: xMEMS Labs
With the vent open, Skyline reduces occlusion effects by up to 27dB@100Hz, making exercise and conference calls more natural and comfortable. Consumers also experience improved spatial awareness, and a more natural passthrough/transparency mode where the voice of the person you're speaking with enters your ear directly through the Skyline vent instead of being digitally amplified and artificially reproduced in most wireless earbuds today.
A low-power "comfort" mode is also available that blends the benefits of open and closed modes at reduced power consumption. Comfort mode brings between 3-8dB of leakage reducing occlusion effects and increasing spatial awareness, while still providing 8-20dB of passive noise isolation.
These benefits apply to hearing aids as well, allowing manufacturers to develop devices that are more comfortable and more adaptable to a wide range of daily usage scenarios. And for wearers, they no longer have to switch between open and close fit ear tips to match their listening environment.
Sleep buds are also growing in popularity, and any progress to make them more comfortable and more automated will undoubtedly encourage increased adoption. With a sensor-activated solid-state vent, sleep buds can block ambient sounds such as snoring or machine noise, then automatically let the ears breathe when the room is quiet.
One Earbud To Rule Them All
We are at an inflection point where personal audio devices are necessary for a significant portion of our day, but the wireless earbud industry has been slow to innovate and often focuses on incremental improvements. Now we have the opportunity to create a major shift in quality and usability that can also improve brand reputation and market share for those who give consumers what they always want: an easy-to-use product that expands usage scenarios, reduces complexity and frustration, and ultimately makes their lives easier.
Solid-state MEMS vent technology is the answer we've been looking for. xMEMS' Skyline, available in a 4x5x1.15mm LGA package along with the companion Alpine controller IC, is mass-production ready. Contact your local xMEMS sales representative or distributor for more information at https://xmems.com/contact/.
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