Innovation in the headphone space has been an intriguing thing to observe and experience over the past decade. R&D focused on wireless and driver technologies have propelled the personal audio category into a very different place; both in terms of sales, sound quality, and mainstream acceptance. xMEMS Labs, makers of solid-state, all-silicon micro speakers has announced its next innovation in sound reproduction for TWS (True Wireless Stereo) earbuds.
Designated as Cypress, xMEMS claims this new solid-state MEMS speaker is designed to replace legacy push-air sound reproduction with richer, more detailed, bass-heavy, high-fidelity sound. Cypress represents the first alternative to the moving-coil concept for high-volume consumer active noise canceling (ANC) earbud microspeakers.
From Mike Housholder, Vice President, Marketing and Business Development for xMEMS: “By shifting to a sound from ultrasound principle, the xMEMS Cypress micro speaker can now officially replace traditional coil-and-magnet speakers in active noise canceling earbuds…Cypress maintains all of the benefits of xMEMS’ existing speakers while being 40x louder in low frequencies, achieving a key requirement for ANC earbuds.”
Cypress Audio Tech Basics
Legacy coil speakers generate sound in the audible band, which is intrinsically inefficient. XMEMS claims that Cypress takes advantage of the characteristics unique to MEMS drivers —speed, precision, and uniformity—to produce high-resolution audio more efficiently.
As an air pulse generator, Cypress consists of two main parts:
- A modulator to generate an amplitude-modulated ultrasonic wave (carrier) that follows the amplitude of the intended audio signal.
- A demodulator that synchronously demodulates the ultrasonic wave, transferring the acoustic energy down to the baseband, producing the intended audible sound.
The resulting sound envelope of ultrasonic pulses is an exact acoustic copy of the source signal. This means across all frequencies, Cypress is intended to be more faithful to the original recording than current speaker technologies. With superior resolution in the time domain, Cypress is supposed to have the ability to more accurately reproduce advanced sound formats, including high-resolution and spatial audio.
From Jemm Liang, xMEMS CTO: “Cypress not only revolutionizes how sound can be reproduced from an electric signal, but it also redefines how it should be reproduced...”
Cypress Design Characteristics
Here is what xMEMS claims Cypress brings to the table:
- Faster mechanical response which supports improved detail, clarity, and separation
- Near-zero phase shift that provides accurate, unaltered, sound reproduction
- Improved part-to-part phase consistency for better spatial imaging accuracy
- Rigid silicon diaphragms eliminate speaker breakup for improved mid/treble clarity
- Non-magnetic structure that supports lighter weight and reduced electromagnetic interference
- Improved quality, reliability, and part-to-part uniformity from the solid-state semiconductor process.
Miniature Size
Cypress comes in a (9mm-diagonal) 6.3 x 6.5 x 1.65mm package. Despite its very small size, this assembly is designed to bring an added benefit of being 40x louder in low frequencies compared to xMEMS’ prior generation speakers, providing stronger, deeper bass that is consistent with the best 10-12mm legacy coil speakers, including sound pressure levels (SPL) greater than 140 dB as low as 20Hz.
ANC Performance
xMEMS claims that Cypress brings new advantages over legacy coil-based drivers to further improve ANC applications. Its faster electrical-to-acoustic conversion can contribute to wider ANC bandwidth (i.e., an extension of ANC to cancel higher frequency noise sources, like a crying baby).
The near-constant electrical-to-acoustic conversion time (group delay) is intended to reduce DSP filter complexity which, in turn, supports shorter DSP latency, rounding errors, and power consumption when processing ANC.
Availability
Full-function Cypress prototype silicon is now sampling to select early product brand customers. Production-candidate samples of Cypress and the companion Alta controller/amplifier ASIC will be sampled in June 2024. Mass production is planned for late 2024. Actual products may show up on store shelves by 2025.
Tip: xMEMS will demonstrate Cypress by appointment only on January 9-12 at CES 2024 in Las Vegas, NV.
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