Noise cancellation and occupancy zoning provides improved acoustic experience in electric cars
The move to electric drivetrains re-wrote the book on how engineers deal with automotive Noise, Vibration and Harshness (NVH) with some suppliers to the industry taking a prominent role in addressing some of the challenges that the industry faces.
One company, Harman, has a long history in the field of acoustics and the production of sound systems and infotainment products. When electric vehicles first appeared, Harman was already working with car manufacturers on the noise profile of their products.
Over five years ago, undertook significant research with industry partners on road noise cancellation, the result of which was the HALOsonic suite of sound management systems, which continue to be the core of the company’s portfolio today. HALOsound comprises Engine Order Cancellation (EOC) and Electronic Sound Synthesis (ESS) to both enhance engine sound inside the vehicle (internal ESS) and create new sounds for hybrid and electric vehicles to comply with applicable regulations (external ESS).
The HALOsonic iESS is the part of the system that enhances the driving experience. Drivers are accustomed to the audio response of a combustion engine as they accelerate, decelerate and drive around corners, something which is missing in EV products.
To improve the driving experience, this technology enables sound contouring inside the car by creating speed- and throttle-dependent sounds through the standard speaker system. The system delivers improved engine feedback and makes drivers feel connected to the car they drive.
The HALOsonic eESS is the part of the system that provides safety to other road users and is designed to meet legal requirements.
The silence of the electric drivetrain means that pedestrians miss familiar acoustic clues warning them about an approaching vehicle. With an electric vehicle, they can no longer rely on sound to determine how fast a vehicle is approaching and how close it is.
eESS works by synthesizing engine sounds with volume and pitch appropriate for the speed and direction of the vehicle. This sound is projected from speakers mounted at the front of the vehicle, giving an early warning to pedestrians that the car is approaching. The sound is projected only in the direction of travel, fading away almost instantly once the vehicle has passed.
Active Noise Control
Harman then went on to work with Hyundai on its Road-Noise Active Noise Control (RANC) feature, which is based on HALOsonic technology. RANC was designed to combat road noise to increase driving pleasure by reducing unwanted noise by up to 50 percent. The Korean manufacturer deployed the technology on its Genesis GV80 SUV at its launch in 2020.
Harman distinguishing the roles played by both sound and noise within the vehicle, asserting that sound has an essential role to play in the driving experience whereas noise has a negative, distracting influence. In the development of its products, Harman seeks to reduce noise and enhance desirable sound.
The current drive towards improving vehicle handling and fuel efficiency through, for example, stiffer suspensions and wide low-profile tyres has the disadvantage of offering multiple paths for unwanted noise to be transmitted through the structure of the vehicle, ultimately creating a ‘droning’ noise inside the car cabin that is both distracting and tiring. Applying conventional, passive Noise, Vibration and Harshness (NVH) methods to reduce this intrusive noise significantly adds to the vehicle weight with a further negative effect on fuel economy and CO2 emission levels.
RANC works by using reference signals received from acceleration sensors placed strategically along the suspension and chassis to predict noise transferred into the cabin and to generate an anti-noise wave in real-time. Computing time and signal transfer speeds are optimised to allow for analysis of the intruding noise and the generation of the anti-noise within milliseconds, thereby preventing the noise from reaching the occupants’ ears. Error microphones constantly monitor the system performance in each seat location to ensure a more pleasant ride for all vehicle occupants.
Interior Sound Zones
With a history associated most closely with audio entertainment systems, Harman continues to cater for the needs of car occupants and has applied acoustics technology to the role of customising the audio requirements of individual passengers within the vehicle, most recently through sound zoning and legacy audio system enhancement.
These two products have been launched as “Ready Together” and “Software Enabled Branded Audio”. Ready Together uses advanced acoustic technology to streamline and enhance in-vehicle communication and entertainment. Software Enabled Branded Audio is an on-demand software platform that upgrades the sound quality and feature set of existing unbranded car audio systems with the touch of a button. Both products can be fully integrated into existing products from car manufacturers.
Ready Together delivers better ways for the entire family to be safely connected while enjoying shared or personalised entertainment in the vehicle. It manages and optimises features like voice prompts, alerts and music/media to work together as an integrated whole, for seamless information and communication. Ready Together also uses advanced sound zone technology so that each occupant can enjoy their own media – while also allowing shared experiences and conversation.
Advanced noise management, microphone and voice processing capability enables clear, frustration-free conversations for all vehicle occupants. Dedicated profiles and presets for the driver and each passenger deliver independent entertainment, customised for all types of trips, with no interruptions.
As part of this, Harman has also introduced a “Personal Audio Headrest” as part of the Ready Together system. The Personal Audio Headrest’s unique design is more efficient and streamlined, delivering improved levels of audio performance in an ergonomic and comfortable way. Its modular design allows OEMs seamless in-cabin integration with their preferred seating system. With the ability to adjust their immersion level from 2-channel stereo to full surround sound, passengers can customise an individual car audio experience to suit their personal preferences and needs.
Software Enabled Branded Audio offers consumers a user-friendly and affordable way to elevate and customise their unbranded in-cabin audio systems to deliver the sound and character of Harman’s Infinity brand, on demand and with no additional hardware required. For the first time, an existing unbranded base car audio system can be instantly upgraded to a high-quality branded audio experience.
Software Enabled Branded Audio features personalised audio features and brand-new, customisable sound experiences for any style of listening. It can be introduced at any point in the vehicle’s life and features seat specific tuning optimised for location and number of occupants.
According to Chris Ludwig of Harman International, the company remains focused on delivering new in-vehicle systems that directly solve the challenges faced by vehicle manufacturers, drivers and passengers alike.
“With these latest products, Harman can now provide the whole family with their own personal content and space, while allowing them to remain safely connected and engaged with others while in the car,” he concludes.