Innovation is coming in increasingly smaller packages these days, and solid-state speakers made with silicon and powered by MEMS technology are proving to be the latest example boasting big payoffs despite their minuscule size. In a recent article from The Wall Street Journal, tech columnist Christopher Mims expounds upon the advent of solid-state, wafer-thin silicon speakers powered by MEMS (microelectromechanical systems) technology, which is the same technology that has made it possible for a smartphone to be an mp3 player, a phone, and a calculator, among other things.
Should these speakers become common, they can have wide-reaching impacts on how we experience sound in various products, from smartphones to wireless earbuds to assistive listening devices like hearing aids.
Companies like Austrian USound and California-based xMEMS have developed solid-state silicon speakers for the market, proving that the possibility of all hearing electronics having this technology embedded is closer than we think.
The Progenitors to Solid-State Speakers
As with most innovations, solid-state silicon speakers result from existing technology that has been continually tinkered with over many decades. Mims notes, that speaker technology has changed relatively little since its invention in the early 20th century.
The first working idea for a loudspeaker was introduced by Alexander Graham Bell in 1876, but this was through a horn, which created a muffled sound that contributed to poor audio quality. However, the first modern loudspeaker prototype was developed by Chester W. Rice and Edward W. Kellogg in 1921. The collaborators improved upon existing moving-coil technology developed at Magnavox. Rice and Kellogg patented their technology in 1925, which was used in the first commercial loudspeaker, the dynamic RCA-produced Radiola Loudspeaker #104.
Speaker capability and quality have improved substantially since, but the fundamental technology has changed very little. A magnet inside a speaker is contained within a coil of wire attached to a flexible membrane. When electric pulses travel through the wire, they are turned into vibrations. The membrane translates these vibrations “into the movement of air that we call sound,” as described by Mims.
What makes MEMS solid-state silicon speakers so innovative is that it compresses all the essential parts of a speaker (the magnet, the wire coil, and the flexible membrane) into a compact, single unit. The small size of these speakers offers greater clarity and possibly requires less power.
MEMS Technology Elevates the Listening Experience in Solid-State Speakers
What is this MEMS technology exactly, and what does it do to heighten the listening experience for earbuds users everywhere? The answer lies in piezoelectricity, a scientific phenomenon in which electricity accumulates in certain solid substances when pressure is applied. The piezoelectric effect can occur in “crystals, ceramics, polymers, wood (cellulose fibers), and a host of other synthetic and composite material,” according to ElectronicDesign.com.
Piezoelectricity is applied in the technology of various electronics, from mechanical toothbrushes to smartphones, PCs, and microphones. However, piezoelectricity is especially useful when applied to speakers. ElectronicDesign.com outlines that piezoelectric speakers utilize the inverse piezoelectric effect “to generate and produce sound” by applying a voltage to speakers that produce a vibration, which transforms into sound waves. Piezoelectric speakers produce high-quality audio that is crisper and clearer because they require “a small amount of frequency response.” Furthermore, piezoelectricity is more precise and controllable, which is especially useful for speakers.
The solid-state speaker from the USound Ganymede series has a thin form factor of 1.6 with audio output up to 20kHz. The solid-state speakers from xMEMS are 1 mm thick with a bandwidth of 20Hz-20kHZ. It is no wonder that piezoelectricity, with its powerful audio capabilities produced with little frequency, and solid-state silicon speakers, with small dimensions, are a match made in heaven.
The Future of Solid-State Silicon Speakers, for Earbuds and Beyond
What the development of solid-state silicon speakers means for audio equipment like earphones, headphones, and assistive listening devices is less defined. The main benefits of having such technology are apparent. The piezoelectric capability of MEMS technology paired with the compact solid-state silicon design enhances the auditory experience by making sound crisper and clearer. With a lack of such technology, high-end earbuds and over-the-ear headphones cannot boast such high quality.
Then there is the consideration of accessibility. The CDC documented that 13 percent of adults ages 18 and over reported some difficulty hearing even when using hearing aids in 2019. When taking this into account, solid-state silicon speakers with MEMS technology become especially transformative when applied to assistive listening devices like hearing aids and implants. USound just recently partnered with OTC hearing aid company Linner to develop OTC hearing devices featuring their Conamara 6mm full-range speakers.
However innovative solid-state silicon speakers prove to be, they have a long way to go before becoming the standard technology used in the wireless earbuds we know and love. Though it will be a while before all listening devices have solid-state silicon speakers embedded, the technology is here, and the future of sound is becoming more dimensional and defined.