Knowles MEMS Microphones Amplify In-Car Audio

Article By : Anne-Françoise Pelé

Knowles is sampling two MEMS microphones to support the growing demand of the automotive market for hands-free calling, advanced voice assistance, and in-cabin noise cancellation.

Sensors such as MEMS microphones have become critical enablers of human-machine interactions in cars. Illinois-based Knowles announced it is sampling two MEMS microphones to support the growing demand of the automotive market for hands-free calling, advanced voice assistance, and in-cabin noise cancellation.

In-cabin audio

Knowles has expanded its SiSonic MEMS microphone series with the introduction of the SPH1878 and SPH9855 to provide carmakers with additional capabilities to develop enhanced voice call quality and in-cabin audio features.


More than 16 million premium automotive audio systems will be shipped by 2025, according to SAR Insight & Consulting’s latest report on the topic, “In-Car Audio Distribution: The Connection Between Audio and Vehicle Brands.” In a recent discussion with EE Times EuropeDennis Goldenson, director of artificial intelligence and machine learning at SAR Insight & Consulting, assessed that close to one-fifth of new vehicles produced globally now include a premium audio system. “With over 50 million mid-range and luxury vehicles being produced annually in 2020, growing to 70 million by 2025, we can expect to see a growing trend in the advancement of network-enabled infotainment systems.”

The performance of the SPH1878 and SPH9855 MEMS microphones is “quite versatile” so that they are suitable for a variety of use cases in both premium and mainstream audio segments, Greg Doll, general manager and vice president of product management at Knowles, told EE Times Europe. These include background noise suppression and the ability to make the cabin quieter by cancelling engine and road noise.

“These products targeted at automotive use cases offer tighter performance tolerances and higher reliability defined by the automotive AEC-Q103 standard,” said Doll. “They also leverage the many benefits of our standard technology like high dynamic range to capture sound without distortion as well as broad frequency range to enable multiple use cases.”

These microphones, Doll continued, are tuned to pick-up very low frequency sounds like the wind, road, and engine noises with low distortion in order to generate the exact opposite waves through the speaker system to cancel the noise. “For this noise cancelling to work well, the mics have to be of high quality so they not only pick-up as much noise from the environment as possible but also do so while avoiding adding any noise of their own to the system. These new mics are designed to do just that.”

Knowles SPH9855 MEMS Microphone
Knowles’ SPH9855 MEMS Microphone
Knowles SPH1878 MEMS Microphone
Knowles’ SPH1878 MEMS Microphone

The electronics within cars are exposed and expected to resist extreme temperatures. In contrast, most consumer electronics devices experience milder temperatures (-20°C to 70°C). Knowles’ SPH1878 and SPH9855 microphones “are designed to operate in extended temperature range, from -40°C to even +85°C,” Doll said.

Knowles also claimed improved manufacturing stability and traceability. These microphone designs are indeed tested and qualified to a higher level of robustness in line with the AEC-Q103 automotive guidelines for microphones, Doll said.

The SPH1878 and SPH9855 microphones are currently sampling with customers and are expected to be in production later this year. “We have our own proprietary MEMS microphone designs that can be scaled from our two multi-national factories at high-volume to provide manufacturing flexibility for our customers,” Doll specified.

Emergency calls

When an emergency takes place or an accident happens, every second counts. The European emergency call system, or eCall, aims to provide rapid assistance to motorists anywhere in the European Union. In the case of an accident, eCall automatically establishes a voice connection to the emergency call center and transmits a data set with information on the accident location. Since April 2018, all new cars must be equipped with the eCall technology.

The SPH1878 and SPH9855 microphones are compatible with the eCall communication system. “eCall and other such standards enabling commuter safety are very effective. Being able to communicate reliably with emergency personnel, if needed, is of paramount importance. Choosing the right components, including high performing, robust microphones is a critical element to enabling this reliable communication.”

Knowles is working closely with several automotive OEMs, tier-ones and system integrators throughout the world as well as in Europe “to help them achieve the level of quality and reliability desired for these emergency call systems,” Doll concluded.

This article was originally published on EE Times Europe.

Anne-Françoise Pelé is editor-in-chief of and EE Times Europe.

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