Molex Enabling Quieter, Smoother EV Rides

Article By : Stephen Las Marias

Clark Chou of Molex talks about the key to effective road noise cancellation in vehicles.

Electric and hybrid cars are making more of an impact on the automotive market as environmental concerns grow. The stringent government rules and regulations toward vehicle emission, along with reduction in cost of electric vehicle (EV) batteries and increasing fuel costs, are driving growth of the global EV market, which is forecast to reach $823.75 billion by 2030, up from $163.01 billion in 2020, according to Allied Market Research.

Apart from their non-existent carbon emissions, EVs are quieter than their combustion engine driven counterparts. And there is the rub.

From an acoustics perspective, occupants have indicated that they perceive higher levels of road noises in EVs.

“Humming, hypnotic road noise, which is a low-frequency broadband sound, transmits from road surfaces into the vehicle along through the tires, suspension, and body components. Without combustion engines to mask it, road noise is more perceptible in EVs,” explains Clark Chou, Senior Director of Sales for Greater China and India, at Molex.

Clark Chou

Chou says traditional noise reduction uses passive methods, ranging from energy absorbing materials such as foam or rubber to the use of air gaps to attenuate acoustic energy.

“The intention is to dissipate energy—vibration—before it reaches the human ear. It is not an inconsiderable challenge, as alternative techniques of noise reduction work better with different frequencies of sound, and no one method can be totally effective,” he says. “In contrast to passive techniques, active noise cancellation (ANC) works by measuring the waveform of the unwanted sound and generating an equivalent inverted signal. This signal is then transmitted alongside the original. The two waveforms, being inverted images of each other, combine and are weakened by the effect of phase cancellation. This, then, reduces the amplitude of the original signal and thereby reduces the volume of the unwanted noise.”

But because of complex wire harnesses and the material they carry, ANC systems were less efficient and less economical than desired.

Key to effective noise cancellation

Automotive applications leave sensors and sound-dampening systems vulnerable to a variety of harsh environmental factors, like water, dust and rocks which can damage the system. However, the key to effective noise cancellation is to place the sensors close to the source of the noise.

“In automotive applications, the sensors need to be located as close to the road as possible, which means mounting them to the underside of the car, thus presenting a range of challenges for the design of the components,” says Chou.

The automotive environment is one of the toughest in the world. Cars and other vehicles are designed to function in a broad range of conditions. Automotive components must also be able to withstand chemical contaminants, including those to deal with snow and ice. Physical risks to equipment must also be considered. Therefore, automotive manufacturers design vehicles with global environments in mind, which means designing vehicles with an undercarriage that can withstand the damage that accompanies driving on rough terrain, and unpaved roads and trails.

“Our Road Noise Cancellation (RNC) Sensors utilize Automotive Audio Bus (A2B) technology paired with a sensing element that captures sound waves, to enable a reduction in road-based noise that a combustion engine would typically mask,” says Chou. “RNC Sensors capture a sound wave as vehicle chassis vibration is detected and transfer it to the processing unit, which generates a cancellation wave form to the sound inside the vehicle while traveling on the road.”

Unique solution

Utilizing the A2B audio bus technology of Analog Devices Inc., Molex’s RNC Sensors are connected through daisy-chained cabling, which eliminates the weight of heavy star-pattern or home-run wire harnessing and sound-dampening materials. The network technology minimizes the time need for the sensor to receive the vibration excitation and for the processing unit to receive the signal, which means the noise is cancelled more efficiently. Plus, the sensors can measure road noise at slower speeds and be placed farther away from the sound source, while providing more network data channels as well.

Furthermore, the casings for the sensors were designed to anticipate the water and dust of the harsh automotive environment; they carry an IP6K9K enclosure rating to protect the system, utilizing the space-saving Molex Sealed Mini50 Connector interface. Various mechanical housing configurations offer flexibility for orienting the sensing element parallel or perpendicular to the ground, which allows for a variety of connector orientations and terminal sizes. Moreover, RNC systems can be configured with four to eight sensors, depending on need.

On top of this, advancements in noise cancellation technology have accelerated, thanks to the collaboration between Bose and Molex.

“To combat unwanted road noise, these innovators validated and integrated Molex’s automotive ANC accelerometer-based sensors with Bose’s QuietComfort Road Noise Control technology for industry-leading performance and quieter, more enjoyable driving,” says Chou.

Molex’s family of ANC accelerometer and microphone sensors use Analog Devices’ Automotive Audio Bus (A2B) technology to ensure delivery of high-fidelity audio while significantly reducing cabling complexity, cost, and weight. By pairing its sensors with the A2B network, Molex transmits noise signals to the processing unit in less than 2ms.

According to Chou, Molex also has tested and validated the use of its RNC sensor with Silentium’s “Active Acoustics” software, which removes up to 90% of unwanted noises across a broad band of frequencies (from 20Hz to 1kHz) to improve driver and occupant comfort, safety, and wellbeing. In particular, the elimination of frequent humming or droning noises coming from roads and tires is critical to decreasing “highway hypnosis” and driver fatigue.

Award winner

It is these features that garnered Molex the Best Sensor of the Year award at the recent EE Awards Asia. Now in its second year, EE Awards Asia honors the innovation, creativity, and contributions of Asia’s engineering community that have made a difference in the way we work, live, and communicate over the past year.

EE Awards Asia 2022 has gathered more than 400 entries from 137 companies around the world, vying for 22 award categories.

“Molex is delighted to receive these awards. EE Awards Asia celebrates the best products, companies, and individuals across the continent’s highly regarded electronics industry,” says Chou. “To be judged and selected by a global panel of experts, and then to receive validation from the reader communities of EE Times and EDN in Taiwan and Asia, is gratifying. We are pleased that the experts and customers have recognized our vital role in the automotive industry.”

Molex’s experience extends to all corners of the automotive ecosystem. “For decades, our role in the automotive industry has been elevated by the company’s heritage in the data center, telecom, networking, and consumer electronics industries. For the automotive sector, Molex designs and delivers critical electronics, connectivity, high-speed networking, data storage as well as power and signal solutions that form the central nervous system of tomorrow’s next-generation vehicle architectures,” Chou adds.


Chou says they anticipate seeing increased investment in applications using real-time data to propel major advancements in sectors such as automotive, consumer devices, data center, and connected healthcare markets.

“The emergence of powerful applications, such as artificial intelligence (AI), AR/VR, digital twins, sensors, and machine learning (ML), benefit from connected data to deliver unprecedented customer value, starting with product design and ideation and extending to supply chain intelligence, advanced manufacturing and fulfilment,” says Chou.

The automotive industry continues to advance at unprecedented speed, and automakers along with Tier 1 and 2 suppliers must react with ever-increasing precision. Next-generation vehicle architectures require ever-increasing connection points carrying more content than ever before and automakers are seeking products that enable higher speeds, and therefore, more data while also meeting their exacting harsh environment standards.

Molex expects to see the following automotive applications to put data front and center including, advanced driver assistance systems (ADAS), which will depend on data from a constellation of sensors, from cameras and LIDAR systems to AI applications that analyze data, identify road hazards and present information in intuitive, integrated displays; and automakers’ prescriptive moves to enable Level 2 and Level 3 autonomy.

“Major investments in battery management, zonal architectures, and EV charging stations will dominate. Emerging demand for Infrastructure advancements is expected to escalate over the next 12-to-18 months, which will also place greater emphasis on the need for intelligent sensors and high-speed connectors,” concludes Chou.


Stephen Las Marias is the editor of EE Times Asia/India. He can be reached at


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