5 hours Ago By Peter Holmes
A new xMEMS micro speaker that creates “sound from ultrasound” will go into mass production in the first half of 2025. xMEMS Cypress is being positioned as the world’s first “full-range, solid-state MEMS speaker for Active Noise Cancellation (ANC) earbuds”, and the manufacturer says it is a “no-compromise replacement for coil and magnet speakers in ANC earbuds”. Cypress generates sound through ultrasound modulation-demodulation.
“Ultrasonic speakers beat out dynamic counterparts in SPL [sound pressure level], frequency response, phase response, and THD [total harmonic distortion], and let’s not forget greater design flexibility,” said Robb Zimmerman, Principal Systems Engineer at xMEM Labs. A Yamaha earbud. “With the invention of the dynamic driver speaker celebrating 100 years, it’s an opportune moment to reflect on this widely recognised, coil-based transducer that delivers sound in almost all TWS [True Wireless Stereo] earbuds available today.
” Zimmerman said that while the technology had evolved over a century “due to progress in physics, materials, and simulation”, the fundamentals have remained the same. “In a dynamic driver speaker, the speaker’s diaphragm directly displaces air by moving at audible frequencies to create audible sound,” Zimmerman said. “Other transducer innovations – electrostatic, planar magnetic, and now even solid-state MEMS transducers – have moved the industry forward, but they all share the same ‘push-air’ concept, along with their associated product design and performance limitations.
” He said a few startups, including xMEMS, have “leveraged the superior characteristics of silicon and piezoelectric materials to enable previously unachievable bandwidth, musical detail and performance in micro speakers”. xMEMS Cypress – “sound from ultrasound”. “However,” he added, “it’s the upcoming advancements in MEMS transducers that hold the greatest potential for revolutionising the field.
” Cypress is driven by a companion integrated circuit called Alta. “Operating closer to AM radio frequency than audible sound, Cypress and Alta work in concert to convert analog voltage into acoustic air pulses,” Zimmerman said. “Alta modulates the incoming baseband signal into a Dual Sideband Suppressed Carrier (DSB-SC) AM signal, and Cypress demodulates in the acoustic domain, generating high-frequency air pulses.
” xMEMS said Cypress and Alta will be combined in an “easy-to-integrate” System-in-Package (SiP) that acts as a drop-in replacement for typical dynamic drivers found in TWS earbuds. “Sound from ultrasound has been a research topic since the 1960s but has never achieved the acoustic performance required for broad commercial appeal, until now,” Zimmerman said. “In the near future, TWS earbuds will leverage a MEMS micro speaker that creates audible sound through ultrasonic waves .
.. that would otherwise go undetected by the human ear.
He said that, instead, our ears will hear “rich, detailed, bass-heavy, high-fidelity sound”. To do so, a companion controller/amplifier ASIC is needed to modulate the audio into ultrasonic carrier signals, which drive the MEMS speaker to create acoustic air pulses, Zimmerman said..
