xMEMS announces sound reproduction breakthrough with latest speaker

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xMEMS Labs, a developer of solid-state, all-silicon micro speakers, has announced what it says is a radical breakthrough in sound reproduction.

The company claims that its latest solid-sate MEMs speaker will change the way true wireless stereo (TWS) earbuds create ultra high-quality, high-resolution sound experiences across all audio frequencies.

With its 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 alternative to the moving-coil concept for high-volume consumer active noise cancelling (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 cancelling 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.”

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

Until this launch, sound from ultrasound had been a research topic but had never achieved the acoustic performance required for broad commercial appeal.

As an air pulse generator, Cypress comprises: a modulator to generate an amplitude-modulated ultrasonic wave (carrier) that accurately 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 it can more accurately reproduce advanced sound formats, including high-resolution and spatial audio.

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

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 unrivalled 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

The Cypress speaker comes in  a 6.3 x 6.5 x 1.65mm package (9mm-diagonal) and is 40x louder in low frequencies compared to xMEMS’ prior generation speakers, providing a stronger, deeper bass that is consistent with the best 10-12mm legacy coil speakers, including sound pressure levels (SPL) greater than 140dB and as low as 20Hz.

This additional low frequency SPL is critical for ANC earbuds.

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.

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.