Write a commentAs I mentioned last month, one of the things I planned to check out at CES was MEMS, or micro-electromechanical systems. These tiny devices, made by California-based xMEMS Labs, are a different type of driver for both earphones and headphones. I was able to get a closer look not just at the currently available drivers like what you’d find in the Creative Aurvana Ace Mimi earphones, but some upcoming variations and several other uses of the technology that look equally, if not more, fascinating.
Drivers
Nearly all headphones and earphones use dynamic, balanced armature, planar magnetic, or electrostatic drivers. Some use a combination, especially with dynamic and BA. MEMS are a different kind of driver, and quite new for headphones and earphones. It’s essentially a solid-state driver, a speaker on a chip, if you will, that uses the piezoelectric effect instead of moving a diaphragm using electromagnetic energy.
There are pros and cons with any technology, and with MEMS the pros are consistency in manufacturing for easier driver matching, water resistance, size, and fast response times. For earphone use, the biggest downside is that despite their prowess with treble, they haven’t done well with bass—at least so far. This is why current implementations of MEMS drivers, including the aforementioned and reviewed Aurvana Ace Mimis, typically pair them with a dynamic driver.
At CES, xMEMS showed its Sycamore chip, which is a full-range driver for earphones, smartwatches, and other wearables. What’s quite fascinating, well, more fascinating even than MEMS tech in general, is how it’s creating sound. The part of the driver creating the sound you hear is actuated by a MEMS device creating ultrasound. Wild. Like a bee flapping its wings on the head of a timpani and somehow being as loud as a drummer with a mallet. I got to hear the Sycamore chip in some hand-built prototypes, and they definitely had bass. We’ll have to wait to see how these drivers are used and tuned in actual products.
MEMS aren’t just for earbuds. xMEMS also had some pre-production over-ear headphones from one of its partners that have a large dynamic driver paired with a MEMS “tweeter.” One of the benefits xMEMS claims for its tech is that its better consistency between drivers means spatial audio can be more accurate. The company had a demo set up for this as well, and while it was compelling, spatial audio is complex.
Barn doors
xMEMS also showed its Skyline chip, essentially micro-sized barn doors for earbuds. These tiny doors can let a single earbud function as both a closed-back and open-back design. Want to be closed off from the world with a bit of quiet? Close the doors. Want to hear the world around you? Open the doors. This would be done in the app, or maybe by tapping an earbud.
I was skeptical that this would do much, given that the “doors,” or what xMEMS calls an acoustic vent, are of course tiny. The demo let me open and close them with a push of a button, and it was surprisingly effective. When open, there was noticeably more ambient sound compared to closed, and said sound was far more natural than the amplified “aware mode” that many noise-canceling earphones have. This was at CES, of course, so we’ll have to wait to see where and how these are implemented.
Your biggest (mini) fans
While the headphone/earphone tech is certainly cool, there was another use of the technology that I think is even cooler. Literally cooler: tiny fans. Only fans, if you will, that are the same size and shape as their earphone drivers. Each 1mm-thick “micro cooling fan” blows a steady stream of air using a tiny fraction of the space that’d be required by a traditional fan design. We’re not talking hurricane-force winds here, of course, but there are countless situations where any air movement will drastically help heat buildup.
You might be thinking, “So?” But ask any engineer, and you’ll get an earful of hot breath about heat management. Heat is the enemy of all electronics, and as devices get smaller and processors faster, heat buildup becomes a bigger and bigger issue. Take your phone, for example. No doubt if you’ve been using it for an extended period, especially if the screen brightness has been cranked up, you’ve felt it get hot. If you’ve used it outside in the summer, you might have even gotten a heat warning. When the phone senses it’s getting too hot, it will throttle down so it doesn’t cook itself and cause permanent damage. Phones are too small for a traditional fan, but one or more of these micro fans could do wonders. It wouldn’t just be to keep them cool in the summer, but also to potentially allow faster processors that would otherwise run too hot for traditional passive cooling designs.
Phones are just one use. There are countless. To be honest, these blew me away, pun intended, more than anything else I saw at the show. Earbud drivers are cool, but these tiny fans could be indispensable everywhere.
. . . Geoffrey Morrison
