The best wireless earbuds have worked the same way for decades now. Similar to big over-ear cans, there are drivers within each that transform the digital signal of any song you listen to into a mechanical vibration that pushes air into your ears as sound waves.
Things have moved on a little bit from this, courtesy of XMEMS with an additional tiny speaker that operates in tandem with the traditional driver to better separate the highs, mids and lows of any song you listen to, while offering better spatial audio.
But after a couple of years of work, xMEMS has arrived at the next generation — ultrasound through a solid-state speaker. This tiny, 1mm-thin speaker is called Cypress, and after listening to it at CES 2025, this company has completely changed the way I think about earbud sound quality.
How does it work?
It’s all rather similar in a way — digital signals translated into audio signals. The main difference is that rather than a mechanical driver that pumps out sound waves through the air, this does so through ultrasonic waves.
This means they can do two key things really well. First, they can sound really good with extremely low latency (more on that later). Second, this tech can achieve a 140-decibel sound pressure level (SPL) at 20Hz. Translation: you can get top-notch Active Noise Cancelation without the need for vents to equalize the pressure, which can cause sound leaks.
Also, for those curious, that piece of silicon these are hooked up to is purely because this is a prototype. All of this will be compressed into the buds that companies who decide to use this driver tech will make.
How’s the sound?
But let’s get to the main event here. Over my years of testing earbuds, I’ve landed on two challenging test tracks — "A Day in the Life" by The Beatles and "Knights of Cydonia" by Muse. The former packs a cacophonic uprising of a 100-piece orchestra that really helps you spot the wheat from the chaff in earbuds, and the latter’s final two-minute section adds so many layers of depth (while also being a banger of a riff).
And in short, after a few minutes of listening, I was left taking these earbuds out and saying “holy…” well, you can fill in the second word of that yourself. The detail across the entire soundstage is unlike anything I’ve heard before — from deep lows to shining highs and well defined mids that aren’t overwhelmed.
Every instrument in that aforementioned orchestral crescendo has its own space to breathe and express, while every new layer of electronic tones and voices singing “no-one’s gonna take me alive” in Muse’s masterpiece are excellently handled through ultrasound.
Outlook
And so, I walked out of that hotel suite and popped in my AirPods Pro 2 — listening to the same songs, I could immediately tell that something was missing. Not to say they sound bad, but some of that crisp detail is just not present in the more traditional driver audio production.
xMEMS has successfully ruined my buds for me. I hope you’re feeling proud of yourselves over there! Cypress is easily the next generation of earbud audio tech in my mind, and I can’t wait to see what the company’s partners like Creative make for it.
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