Qualité acoustique et vibratoire - développements ciblés

Subaru wanted to identify the sources of vibroacoustic emissions that drivers both hear and feel, understand their sound and vibration strengths and weaknesses, and thereby ensure it was continuing to deliver what customers want from their current and future vehicles in terms of NVH performance and character.

We worked together with Subaru at the Application Research Centre and conducted numerous in-depth subjective and objective studies of sound and vibration of both their own and competitors’ vehicles. A test-based SPC model was built to predict the noise contributions from different sources and to identify the dominant sources and paths affecting these contributions. And to ensure that customers’ expectations were met, another project was developed to create sound quality targets and a subjective jury evaluation using the Brüel & Kjær NVH Simulator.

We were able to help the Subaru fine-tune their existing sounds – identifying sounds that customers found desirable in some vehicles but not others – and create virtual prototypes for developing the characteristics of future vehicles.

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Acoustic brand management allows for better brand differentiation, higher brand recognition, stronger emotional reaction from consumers, and therefore an improved experience of the brand.

An automotive OEM wished to develop a brand sound identity for one of its vehicle lines. The vehicle OEM also needed to develop powertrain Sound Quality (SQ) metrics correlated to the Brand Image. To this end, binaural acoustic data was collected at the driver and passenger’s positions while driving both OEM and competitive vehicles on the road in normal driving conditions.

We developed a software application specifically for the subjective evaluation of the recorded sounds on the Powerful/Refined plane. Sounds were grouped by vehicle segment and compared to the SQ Metrics to show what features of sound correlated best to each of those descriptions. The OEM was able to use this information to define sound quality design targets.

An automotive OEM wanted to investigate the mechanisms affecting the perception of impact harshness and develop objective metrics for both acoustic and tactile cues. Operating acoustic and vibration measurements at the human-vehicle interfaces were conducted on-road during the subjective assessment. Operating deflection shapes (ODS), wavelet spectrograms, time domain (envelope), frequency domain (energy spectral density), sound quality, and vibration quality metrics were all measured/calculated to identifying the relative importance (contribution) to overall perceived impact harshness of the different vehicle interfaces. A preliminary model of impact harshness perception was developed along with a recommended roadmap for further refinement by leveraging in-lab simulation tools in place of actual road tests.

An automotive OEM wanted to identify objective metrics for the perceived quality of door closure sound. Acoustic binaural data were recorded from door closure events of multiple vehicles. A formal jury test was designed and conducted and the results were used to develop a functional relationship between perceived sound quality and objective signal parameters. This allowed the vehicle OEM to develop objective sound quality targets to be used during vehicle development.