ESRs & Workpackages

ESR1 will work on the development of a methodology for the auralisation of the vehicle noise transfer path by the hybrid application of both deterministic low-frequency and averaged high-frequency numerical modelling approaches and time domain techniques. After the definition of a general modelling methodology, the approach will be validated with measurements on a vehicle application.

Innovative aspects: full frequency modelling and binaural auralisation of vehicle noise for subjective assessments

ESR2 will focus on the development of acoustic trim materials for noise abatement. Given alternative vehicle powertrains with novel noise characteristics, optimised noise treatments have to be developed combining good acoustic performance with low weight and reasonable thermal performance. Innovative concepts such as meta-materials hold potential for blocking noise in certain frequency bands by tuning the material’s internal design.

Innovative aspects: design and development of novel noise abatement materials

ESR3 will be devoted to the development of warning sounds which can be easily detected by hearing-impaired pedestrians. Approximately a third of the population of people aged 60 and more suffer from some hearing loss. Existing warning sounds have been defined from studies involving normal hearing people only. Some work is needed to evaluate the efficiency of these sounds for hearing impaired people. The detectability of sounds, as well as the ability to quickly identify the approaching direction of the car, will be evaluated in different situations.

Innovative aspects: design of warning sound taking account of imperfect hearing abilities.

ESR4 will develop acoustical techniques dedicated to finely understanding vehicle noise sources on an experimental basis and hence to feed the transfer path. The central idea is to expand the overall radiated noise measured on an array of microphones into a “causal sum” of spatial distributions of acoustical sources originating from distinct physical phenomena. The ambition is to respond to an everlasting industrial need for identifying, localising, and ranking superposed noise sources of various origins.

Innovative aspects: identification and ranking of individual vehicle noise sources

ESR5 will investigate artificial sound sources designed to warn pedestrians of their approach. The level of the noise for such sources in the forward direction is determined by the requirements of audibility. The drive-by noise, however, is also determined by the directivity of the source of warning sounds. This project would consider designs in which the directivity was optimised to minimise the drive-by noise, while maintaining an appropriate level in the forward direction. In particular, a novel directional line-implemented sound source will be considered.

Innovative aspects: novel sound emitting device development with enhanced directivity

Pass-by noise is often estimated, in a laboratory environment with a vehicle on a rolling road, using a microphone array to simulate the effect of motion. The surrounding environment must be completely anechoic for such an estimate to be accurate, which is expensive and difficult to achieve. ESR6 will consider a microphone array processed using a combination of time varying weights, to stimulate the drive-by conditions, but also with additional directivity to focus on the relevant part of the stationary vehicle and so reduce the effect of reflections.

Innovative aspects: microphone array processing including directivity information for pass-by noise

ESR7 will carry out research in assessing the real-world noise emission from road transport by employing reduced source modeling combined with real-world operation data. In detail, ESR7 will develop and extend state-of-the-art source models for predicting the noise footprint from road transport. Large-scale real-world data, collected by diverse databases (e.g. open source data bases such as kolntrace.project.citi-lab.fr, European Data Portal, opentraffic.io), will be used in order to perform statistical time-space analyses and scenario evaluations.

Innovative aspects: Applying noise source modeling of individual vehicles to large collectives of vehicles by employing big data; Analyzing noise scenarios in the context of the on-going electrification of urban road transport; Evaluating the real world effectiveness of (future) regulatory actions for reducing transport noise emissions

The patch transfer function (PTF) approach is a sub-structuring technique for efficient analysis of complex vibro-acoustic problems. ESR8 shall investigate the noise generation and propagation mechanisms during vehicle pass-by manoeuvers by applying a PTF-based approach. A particular emphasis shall be put on proper description of the sound insulation blankets which are commonly used for powertrain encapsulation. Numerical full-system simulations and/or measurement campaigns will be conducted to validate the approach proposed.

Innovative aspects: new PTF approach for powertrain pass-by noise optimisation

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ESR9 will develop a virtual car sound synthesis platform for pass-by noise, combining a vehicle dynamics model with complex networks of noise source models and transfer paths allowing virtual pass-by noise assessment. A major challenge is to realize real-time synthesis performance, requiring ultra-fast and low-latency FIR filter implementations. Virtual pass-by noise predictions will be made for various driving scenarios, vehicle designs and engine control settings. Specifically in view of electrified vehicles, the sound synthesis tool will be complemented with a warning sound generator, enabling the design of optimized warning sounds to alert pedestrians.

Innovative aspects: development of virtual car sound synthesis platform

ESR10 will develop and validate a hybrid PBN engineering technique that allows quantifying the PBN contribution of vehicle subsystem components early in the design. This will be achieved by combining source component models obtained from test bench measurements with vehicle noise transfer functions coming from numerical simulations. By doing so, the effects of engine control settings and vehicle design changes can be evaluated in an early stage. The technique will be elaborated for powertrain and tires, and validated by vehicle measurements.

Innovative aspects: development of hybrid approaches for transfer path input definition

ESR11 will investigate links between tire parameters and psychoacoustic perception of tire-road noise by receivers with the objective to enhance the detectability and reducing the annoyance of tire noise at low speeds. This research is inspired by the fact that tire-road noise is mainly present at higher speeds and as such cannot directly be used for warning vulnerable road users at low speeds when quiet vehicles are approaching. By increasing the detectability at lower speeds, pedestrian safety can be enhanced.

Innovative aspects: making tires more acoustically detectable at low speeds

Goal of ESR12 is the characterisation of dynamic loads on electric and electronic components and the alleviation of those loads by the use of innovative concepts. These components are subjected to various sources of vibrations, depending on the respective installation area. There is a growing trend to move or even integrate power electronics onto or into the housings of electric machines. Currently, electronics are typically not designed to sustain such loads. The first step is it to fully understand what vibrational loads occur and then to try and alleviate the vibration on highly loaded components. Reducing vibration levels will directly also reduce noise.

Innovative aspects: insights in component vibration levels and development of innovative mitigation solutions

ESR13 will develop a (fully) predictive approach to calculate the dynamic excitation forces in the footprint when a tire rolls on a rough road. This parameter is directly related to the structural noise radiated by the tire. Objective is to develop an approach which is numerically efficient. Absolute accuracy is not required as an accurate ranking of different tire constructions will provide the necessary design information and will aid designers in controlling spindle forces/moments and structural tire noise radiation and efficiently explore the tire design space.

Innovative aspects: novel predictive approach for dynamic forces in coarse road-tire contact

Ever more stringent pass by noise regulations in combination with the recent emergence of EV mobility are creating continuous changing vehicle soundscapes & uncharted customer expectations. Future vehicles with reduced powertrain sounds can no longer sustain an appropriate  level of informative & emotional feedback with humans out- & inside the vehicle, nor can they guarantee masking of unwanted interior noises. The need therefore rises for new (synthetic) sounds which can provide suitable acoustic feedback for different levels of human-vehicle interaction while maintaining a comfortable acoustic environment. With increasing application of ADAS, the vehicle soundscape will ever more contribute to vehicle safety e.g. by creating a continuous situational awareness for surrounding pedestrians & occupants or by notifying the need for control take-over from the vehicle.

In order to prepare the ideal future vehicle soundscape, the objective of ESR14 is to create prediction models for comfort perception & safety recognition, for acoustic stimuli  in relation to other cognitive stimuli (vestibular, visual). By correlating acoustic KPI’s with these models, a soundscape for a  specific case study will be proposed & validated for a specific case study.

Innovative aspects : Prediction of human sound quality perception & action recognition for new artificial interior sounds by means of neural networks.