Sound from Ultrasound: Audio Pioneer xMEMS’ New Silicon Speaker Reinvents How Humans Experience Sound

The new Cypress MEMS speaker achieves 40X louder bass response and will be demonstrated at CES 2024 by appointment only. Mass production late 2024.

An industry-first, Cypress achieves >140dB low frequency sound pressure level (SPL), enabling a no-compromise replacement for legacy, century-old coil speakers in noise canceling earbuds.

xMEMS Labs, pioneers in solid-state, all-silicon micro speakers, today announced a revolutionary breakthrough in sound reproduction, changing the way mass-market, true wireless stereo (TWS) earbuds create ultra high-quality, high-resolution sound experiences across all audio frequencies.

With the introduction of its groundbreaking new Cypress solid-state MEMS speaker, xMEMS engineers have replaced legacy push-air sound reproduction with the company’s ultrasonic amplitude modulation transduction principle. Ultrasonic modulation turns ultrasonic air pulses into rich, detailed, bass-heavy, high-fidelity sound, representing the first no-compromise alternative to the moving-coil concept for high-volume consumer active noise canceling (ANC) earbud micro speakers.

“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,” said Mike Housholder, Vice President, Marketing & Business Development for xMEMS. “Cypress maintains all of the benefits of xMEMS’ existing speakers, while being 40x louder in low frequencies, achieving a key requirement for ANC earbuds.”

How Cypress Creates the World’s Best Audio Experience

Legacy coil speakers generate sound in the audible band, which is intrinsically inefficient. Cypress takes advantage of the characteristics unique to MEMS—speed, precision, and uniformity—to produce high-resolution audio more efficiently.

Sound from ultrasound has been a research topic since the 1960s but has never achieved the acoustic performance required for broad commercial appeal, until xMEMS’ Cypress.

As an air pulse generator, Cypress comprises: a modulator to generate an amplitude-modulated ultrasonic wave (carrier) that faithfully follows the amplitude of the intended audio signal; and a demodulator to synchronously demodulate the ultrasonic wave, transferring the acoustic energy down to the baseband, producing the intended audible sound as a result.

The sound envelope of ultrasonic pulses is an exact acoustic copy of the source signal, meaning across all frequencies, Cypress is more faithful to the original recording than current speaker technologies. As a result of its superior resolution in the time domain, Cypress can more accurately reproduce today’s advanced sound formats, including high-resolution and spatial audio.

“Cypress not only revolutionizes how sound can be reproduced from an electric signal, but it also redefines how it should be reproduced,” said Jemm Liang, xMEMS CTO.

Based on Proven Innovation in MEMS Design

Cypress leverages the same production-proven MEMS platform used for all existing xMEMS products and exploits all the benefits of xMEMS’ established solid-state speaker designs when compared to legacy coil architectures, including:

• Faster mechanical response for unrivaled detail, clarity, and separation
• Near-zero phase shift for the most accurate, unaltered sound reproduction
• Superior part-to-part phase consistency for unparalleled spatial imaging accuracy
• Rigid silicon diaphragms eliminate speaker breakup for unmatched mid/treble clarity
• Non-magnetic, for lower weight and reduced electromagnetic interference
• Superior quality, reliability and part-to-part uniformity from the solid-state semiconductor process

Now Cypress, in a 6.3 x 6.5 x 1.65mm package (9mm-diagonal), brings the added and significant 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 140dB as low as 20Hz*.

MEMS and Ultrasonic Modulation Ideal for ANC Performance

This additional low-frequency SPL is most critical for ANC earbuds. With Cypress, xMEMS brings unique advantages over legacy coil to further improve ANC applications. Cypress’ faster electrical-to-acoustic conversion can contribute to wider ANC bandwidth (i.e., extension of ANC to cancel higher frequency noise sources, like a crying baby). Plus, Cypress’ near-constant electrical-to-acoustic conversion time (group delay), can reduce DSP filter complexity which, in turn, leads to shorter DSP latency, rounding errors, and power consumption when processing ANC.

Availability

Full-function Cypress prototype silicon is now sampling to select early customers. Production-candidate samples of Cypress and the companion Alta controller/amplifier ASIC will sample in June 2024. Mass production is planned for late-2024.

xMEMS will demonstrate Cypress by appointment only January 9-12 at CES 2024 in Las Vegas, NV.

For more information about xMEMS and its solid-state fidelity solutions, visit www.xmems.com

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