MEMS Silicon Speaker Achieves Breakthrough with Sound Levels Exceeding 140 dB in Low-Frequency Range
Utilizing a novel ultrasound method, xMEMS Labs has engineered a groundbreaking MEMS speaker known as "Cypress" that delivers commanding sound throughout an extensive audio frequency range, propelling next-generation applications forward.
Marking a significant advancement in the domain of solid-state audio devices, xMEMS Labs is proud to unveil "Cypress," a state-of-the-art MEMS speaker primed to deliver superior sound quality across the full audio spectrum. Solid-state audio technology, though offering a myriad of benefits relative to traditional coil-and-magnet speaker systems, has struggled to match the performance of conventional audio devices—until the emergence of "Cypress," an innovation poised to alter this narrative.
The "Cypress" by xMEMS takes advantage of piezoelectric substances applied to silicon substrates to generate potent audio across a vast frequency spectrum, achieving a remarkable 140 dB at 20 Hz, which is essential for adaptive noise cancellation applications. Image courtesy of xMEMS.
In pursuit of a deeper understanding of "Cypress" and its underlying MEMS speaker technology, we engaged with Mike Housholder, Vice President of Marketing and Business Development at xMEMS Labs, to explore what enables the "Cypress" speaker to excel over a wide frequency range and how adopting solid-state speaker technology can revolutionize the creation of sound in future applications.
Solid-State Ultrasonic Speakers
Solid-state speakers, which harness MEMS technology in lieu of conventional coils and magnets, permit designers to utilize established silicon fabrication techniques to produce audio transducers with superior part-to-part tolerance and consistency. This factor becomes increasingly important as electronics diminish in size, with solid-state speakers offering the potential to maintain audio quality in more compact forms and with a simplified production process.
In contrast, coil-based speakers encompass more intricate components, adding to manufacturing complexity and variability in the end product. Image courtesy of Stetron.
Mike Housholder highlighted the consistency gains of solid-state speakers. "In terms of volume and phase synchronization, manufacturers now receive speakers that no longer necessitate sorting," Housholder explained.
"They can simply select any pair of speakers off a tape and reel or from a tray, fit them into left and right earbuds, and experience perfect matching."
Nevertheless, at lower frequencies, the smaller dimensions and inherent design constraints of solid-state speakers typically hinder their performance relative to larger coil-and-magnet systems. xMEMS, however, has employed cutting-edge techniques such as ultrasonic sound generation to create a solid-state speaker that competes head-to-head with traditional speakers across diverse applications.
Coherent Sound via Modulation
"Cypress" utilizes ultrasonic pulses to encode audio signals rather than creating sound waves directly through air compression and rarefaction at audible frequencies. The encoding occurs via a companion chip named "Alta," which modulates the amplitude of ultrasound pulses that piezoelectric valves subsequently demodulate.
This methodology empowers the "Cypress" speaker to produce high-fidelity and robust low-frequency sounds by merging multiple high-frequency pulses, circumventing a significant drawback of previous solid-state speakers.
For scenarios like adaptive noise canceling, where SPL levels of +140 dB are desirable to counter low-frequency interference, preceding models of xMEMS speakers achieved 120 dB at 200 Hz and 110 dB at 1 kHz. Yet, these earlier versions depended on alternative sources, such as coil-driven speakers, for canceling low-frequency noise.
In stark contrast, "Cypress" independently attains the requisite SPL at low frequencies without supplementary sources. Leveraging the ultrasonic sound technology, "Cypress" speakers manage over 140 dB at as low as 20 Hz frequency, endorsing "Cypress" as a standalone noise cancellation solution capable of mitigating exceptionally loud disturbances.
Cypress's innovative usage of ultrasonic pulses encodes the audio signal, and piezoelectric valves demodulate the audio to ensure a uniform response across the entire audio range. Image provided by xMEMS.
Discussing the implications of xMEMS's newest innovation and the enhanced low-frequency output, Housholder stated, "That's the purpose of 'Cypress.' To reintroduce a single, slender speaker competent in all aspects. With 'Cypress,' we're witnessing an upsurge of approximately 40-fold in low-frequency output compared to our previous offerings—a monumental leap forward."
Currently, selective customers are sampling full-function "Cypress" silicon, with mass production slated for late 2024. Designers interested in "Cypress" will have the opportunity to witness demonstrations by appointment at CES 2024.
Transitioning to Solid State
Although not poised to entirely supplant coil-driven speakers, the introduction of thin, efficient, and less mechanically complex solid-state speaker technology represents a substantial boon for both designers and audiophiles.
As the design community starts to explore technologies like "Cypress," it will be fascinating to observe the adjustments and advancements in associated domains such as audio processing and high-fidelity sound, responding to newfound levels of controllability and performance granted by the transition to solid state.
With MEMS technology maturing, solid-state speakers are increasingly becoming viable alternatives to traditional coil-driven designs, affording engineers augmented functionality within more compact confines. Image courtesy of xMEMS.
Regardless of where "Cypress" stands in the coming years, xMEMS envisions that its availability could signal a transformative moment in the audio sector. Housholder expresses enthusiasm, "This represents a legitimate solid-state substitute for arguably the most voluminous segment of the personal audio market. We're thrilled about this prospect."
Should solid-state speakers become the new industry standard, not only designers but also end consumers should be excited about the future of sound.
