In the car of the future audio systems improve safety, enhance the driving experience and contribute towards a greener world.
HARMAN and Lotus Engineering have worked together to jointly develop noise management solutions, using Lotus-patented Active Noise Control Technologies. This patented new technology is presented to the market under the HALOsonic™ technology banner. With its world-renowned audio design and production credentials, HARMAN is the production integrator and supplier, working with Original Equipment Manufacturers on vehicle-specific systems.
Among the pioneering applications are the synthetically generated engine sounds and warning signals for electric and hybrid cars, as well as the compensation of engine and street sounds. HALOsonic™ technology offers a technically sophisticated, efficient solution for every acoustic challenge and is available to car manufacturers throughout the world - either as an integral part of the infotainment system or as an independent unit integrated in the existing sound system.
We distinguish between two technologies
- Electronic Sound Synthesis (ESS) – this generates the desired sound of an engine, either inside or outside the car
- Engine Order Cancellation (EOC) and Road Noise Cancellation (RNC) – this
cancels unwanted noise inside the car caused by enginee vibrations or the road surface
1. Electronic Sound Synthesis (ESS)
External Electronic Sound Synthesis (EESS)
A specified electronic sound is applied to an external speaker system to improve pedestrian safety. The synthesized sound, dependent on speed and direction, is projected from speakers at the front and rear of the vehicle, giving an early identifiable 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. A synthetic engine ‘idle’ sound is also produced when the vehicle is switched on and the handbrake is released – i. e. when the vehicle is in a state ready to move.
Internal Electronic Sound Synthesis (IESS)
ISS allows sound contouring inside the cabin, enhancing the driving experience by creating speed and throttle-dependent sounds audible through the in-car entertainment system. The system delivers audible feedback to drivers even when the engine is almost silent. The system delivers audible feedback to the drivers even when the engine is almost silent. The creation of internal sounds is independent of exterior noise levels and hence legislation requirements.
2. Engine Order and Road Noise Cancellation (EOC and RNC)
Both noise cancelation technologies and interior engine sound can be integrated into the existing audio system within the car, with the addition of between 4 an 8 microphones for EOC and between 4 and 8 accelerometers for RNC, strategically positioned close to the suspension.
Exterior engine sound requires an additional speaker assembly at the front with an optional one at the rear for improved reversing warning. The diagrams show the system content for each of these. They can be single solutions or can be combined in any way and either embedded within a HARMAN audio system or as stand-alone hardware integrated within the existing vehicle entertainment system.
Engine Order Cancellation (EOC)
The noise produced by combustion engine activity and exhaust is substantial. Traditional methods for reducing the transfer of this noise to the cabin have involved using large amounts of NVH material. All of this sound deadening material is heavy, adding weight to the vehicle which transfers to higher CO2 emissions and poorer performance. HALOsonic™ EOC technology use a series of Error Microphones in the cabin which identify the frequencies of noise created. These are relayed to the processor which generates a cancelling frequency played back through the audio system, reducing the noise heard by the occupants.
Road Noise Cancellation (RNC)
Multi link suspensions create multiple noise paths into the vehicle.Bushes are harde for improved handling capability reducing isolation levels. Combined with the universal trend for wider, low profile tyres, road noise emanates through the structure of the vehicle, creating a “droning” noise. This noise can induce driver fatigue and is annoying, with zero purpurse or benefit. As with HALOsonic EOC technology, the series of Error Microphones in the cabin identify the frequencies of noise created. Again, these are relayed to the processsor which generates a canceling frequency played back through the audio system, reducing the noise heard by the occupants.
HALOsonic™ provides greater safety
The increasing number of Hybrids and BEVs on our roads may present a safety concern at low speed as they may not be heard.
HALOsonic’s™ External Sound Synthesis (ESS ) for hybrid and electric vehicles (HEV’s) is a potentially life-saving technology.
Hybrids and BEVs present a safety concern at low speed as they often cannot be heard and recognized, particularly by high risk groups such as the elderly, children, cyclists and particularly the blind and their guide dogs. Several countries such as USA, Japan and parts of Europe are currently reviewing legislation to state that HEVs must emit a recognizable sound above a minimum noise level to help improve pedestrian safety. Special interest organizations, particularly those for the visually impaired, are supporting proposed legislation.
A study by The University of California identified that subjects could correctly judge the approach of a normal combustion engine from a distance of around 28 feet (10m approx), but a HEV ’s approach direction was only detectable from a distance of around seven feet (2.5m approx). This means that a pedestrian would not be able to correctly determine the HEV ’s approach until it was one second away. With the rapid growth in numbers of these vehicles likely in our cities and suburbs, there is a growing demand for a solution to this problem.
HALOsonic’s ESS provides specified electronic sound models applied to an external speaker system to improve pedestrian safet. A synthesised sund, dependent on speed and throttle position, is projected from speakers at the front of the vehicle, making it instantly recognisable that the vehicle is in motion.The external sound produced is thrown forward, so it is concentraded on the danger zone for pedestrians, with little of the ‘wasted’ sound above and to the rear of the vehicle – the usual experience in a vonventional vehicle.
Involvement of the driver
The driving experience in any car is greatly enhanced when the engine sound provides the driver with the sonic feedback relaying rate of acceleration and speed. This sense of involvement is lost in hybrids and BEVs as under battery power there is no recognizable ‘engine’ sound.
Internal Electronic Sound Synthesis (iESS) can create a link to the sensory connection that traditional internal combustion engine (ICE) cars provide, enhancing the driving experience and awareness by creating speed and throttle dependent sounds audible through the in-car entertainment system. The IESS system delivers audible feedback to drivers even when the engine is ‘silent’.
IESS provides ‘sound scaping’ in the cabin, allowing the driver to select their favourite internal combustion engine sound. When driving a hybrid or electric vehicle (HEV) the driver can enjoy listening to the tones of their favourite V12. This sound can be independent from the exterior noise levels, hence avoiding maximum drive by legislation requirements.
This ‘Brand DNA’ can be used in the conventional manner. As engine sound can be a significant feature of a vehicle however, some manufacturers are looking to brand their HEV with a unique ‘electric’ sound.
IESS is useful in all vehicles, not just in Hybrids and BEVs and enables any characteristic sound to be tailored and generated.
Environment
The energy conscious car of tomorrow will be lighter and will increasingly feature new powertrain technologies, such as hybrids, cylinder de-activation, stop/start, 4 cylinder engines without balancer shafts etc, many of which degrade cabin sound quality. This can be partially treated with traditional NVH techniques but these will always add weight, eroding the gains in fuel economy and emissions.
HALOsonic™ noise cancellation solves this problem by acoustically cancelling the unwanted sound with opposing frequencies, creating a quiet zone for each occupant without adding weight.
Along with the previously described benefits to pedestrians, the external sound projected from the vehicle is focused only in the direction of travel and once the car has passed the sound fades away almost instantly, rather than hanging in the air like the conventional exhaust sound of an internal combustion engine and therefore creating minimal amounts of unwanted noise.
Delivered in this directional manner, ESS reduces any reverberation or echo from surrounding buildings, ensuring that members of the public in these roadside buildings, above the first floor will not hear the vehicle as it passes.
ESS generates necessary sound that is useful and eliminates unwanted noise pollution.
The cabin sound quality can be further enhanced by combining this with IESS, providing luxury refinement for the Green car of tomorrow.
Videos of the interview: HALOsonic
You will also find information about HALOsonic™ under: www.harman.com/halosonic