guideline is <strong>to</strong> design the <strong>sound</strong> of a UFO as the cus<strong>to</strong>mer would expect <strong>to</strong> drive it. This process issimilar <strong>to</strong> VSP <strong>sound</strong> designed for Electrical Vehicle where constraints lead <strong>to</strong> imagined <strong>sound</strong>s fromwords or intentions [10] [11]. The creation of this kind of <strong>sound</strong> faces multiple difficulties; one ofthe most important is that the <strong>sound</strong> interpretation for each person leads <strong>to</strong> different aesthetic choicesand cultural aspects being also not insignificant.All these 3 processes are very different, and graphically represented in figure 8.Need analysis <strong>to</strong>olsNeed simulation <strong>to</strong>olsClio V6, analyze<strong>sound</strong> design processObject axeExistingMo<strong>to</strong>cycle, ExpertIn mind<strong>sound</strong> design processAnalyseCreationSound axeVery Old Car ?Out of mindUnrealisticUFO, Product <strong>sound</strong>design processNeed creation <strong>to</strong>olsFigure 8 – Sound/Object 2D graph4.3 Sound choiceDuring R-<strong>sound</strong> development a lot of proposed <strong>sound</strong>s are generated with suggestions from manyemployees. This activity is treated internally more like a “<strong>sound</strong> design championship”. Since all theproposed <strong>sound</strong>s cannot be implemented, a few select <strong>sound</strong>s are shortlisted via a jury panel <strong>to</strong> beimplemented in the MMI.The choice is probably the most difficult stage of the process and in addition <strong>to</strong> acoustic andtechnical constraints, trademark laws have <strong>to</strong> be considered. We can only use images of Renaultgroup vehicles and unbranded vehicles (as UFO or unbranded mo<strong>to</strong>rcycle). Then for recent vehiclesthe link between image and <strong>sound</strong> is driven by the existing <strong>sound</strong> (as Clio V6) and the choice isreduced <strong>to</strong> the binary possibility: do we propose this vehicle <strong>to</strong> our cus<strong>to</strong>mer, yes or no?The choice is more difficult for simulated <strong>sound</strong>s. A jury was used <strong>to</strong> achieve the final list of<strong>sound</strong>s and images, and consisted of style (graphical design), marketing, vehicle project leader,product definition, cus<strong>to</strong>mer satisfaction and 2 acousticians (the people who proposed the <strong>sound</strong>swere excluded from this jury).The choice for futuristic <strong>sound</strong> is even more difficult. The first question is whether <strong>to</strong> propose aUFO <strong>sound</strong> or not? Experts who work on <strong>engine</strong> <strong>sound</strong> for a long time are clearly against this kind of“non physical <strong>sound</strong>”, but marketing and designers accept this as an amusing approach <strong>to</strong>tally inphase with the R-Sound effect product. When we decided <strong>to</strong> propose an UFO in our MMI thequestion was: what should be the <strong>sound</strong> of an UFO? Then the <strong>sound</strong> designer team proposed <strong>sound</strong>sand let the jury picked the final <strong>sound</strong>.4.4 Sounds ValidationValidating <strong>sound</strong>s is quite easy with appropriate <strong>to</strong>ols, and it’s clear that it is impossible <strong>to</strong>8
validate this kind of <strong>sound</strong> with a standard jury testing in a labora<strong>to</strong>ry. The validation must bedynamic, in car and with different levels. We ask ourselves the following questions:- Sound quality level, is the <strong>sound</strong> pleasant? Is the <strong>sound</strong> coherent with image? (recognition)- Is the <strong>sound</strong> able <strong>to</strong> provide additional sensations? (clearly different with original vehicle<strong>sound</strong> and audible)- Is the <strong>sound</strong> adapted <strong>to</strong> every usage of the vehicle?- We also consider that this kind of <strong>enhancement</strong> must respect security aspects, and we checkthat every <strong>sound</strong> leads <strong>to</strong> enhance pleasure for the lowest speeds. Thus we reduce the level of<strong>enhancement</strong> as the speed vehicle increase.It’s important <strong>to</strong> notice that the validation and fine tuning of each <strong>sound</strong> is an iterative processwith in vehicle test driving, measurement and new design until achievement of each validationparameter. The process has been meanly repeated three times for each <strong>sound</strong> <strong>to</strong> get the right <strong>sound</strong>.After that, the porting and implementation was done with a car audio supplier and the Clio 4 with the6 different new <strong>sound</strong>s is now available on the market since 2013.5. CONCLUSIONWe explored a complete Sound Design of Engine Sound process from <strong>sound</strong> recording <strong>to</strong><strong>sound</strong> generation by using the audio stereo system. This process, based on <strong>digital</strong> signal processing,has the following advantages: Cost: The algorithm doesn’t require a lot of computation power. It’s much cheaper than amechanical solution. Freedom: The <strong>sound</strong> designer has no mechanical constraint; the <strong>sound</strong> can be completelynew. Flexibility: The algorithm and the data set of <strong>sound</strong> synthesis can be uploaded at the endof the car’s project life. The <strong>sound</strong> design can be created in parallel with themechanical design. The same <strong>sound</strong> design can also be applied <strong>to</strong> different vehicles. Choice: It’s possible <strong>to</strong> give the choice <strong>to</strong> the driver among several data sets for different<strong>sound</strong> designs. Adaptation: The <strong>sound</strong> design can be adapted <strong>to</strong> different drivers’ preferences. The <strong>sound</strong>design can also have other parameters <strong>to</strong> reduce the <strong>engine</strong> <strong>sound</strong> <strong>enhancement</strong>, forinstance if the driver decides <strong>to</strong> listen <strong>to</strong> music on the car audio system. Environment: The <strong>sound</strong> design by embedded <strong>sound</strong> synthesis is a chip only weighing afew ounces, easily recyclable, with less CO2 <strong>to</strong> manufacture than a mechanical solution.In addition, this solution doesn’t produce any noise annoyance outside of the car. Performance: Because it’s very small and very light, performances like acceleration arebetter. Fuel consumption and CO2 emission are also lower than with a mechanicalsolution.Product development experience at Chrysler Group LLC in USA and implementation experienceat Renault in France validates the ease and flexibility of <strong>sound</strong> design, audio playback andimplementation in-vehicle. In both cases, feedback from the hands-on development experience hasbeen over-whelming positive in achieving the final goal of enhancing the driver’s audio experience.This technology appears <strong>to</strong> be ready for prime-time production implementation, with the biggestchallenge being on how <strong>to</strong> market this feature with potential vehicle buyers in marketplace.6. REFERENCES[1] Emilie Poirson, Jean-François Petiot, Florent Richard « A method for perceptual evaluationof products by naive subjects - application <strong>to</strong> car <strong>engine</strong> <strong>sound</strong>s” published in "International Journalof Industrial Ergonomics 40, 5 (2010) 504-516"[2] Florent Richard, Vincent Roussarie “ Design de l’ambiance sonore d’un véhicule au<strong>to</strong>mobile– Méthode et outil pour le contrôle de la coloration moteur” published in "Acoustique et TechniqueSpecial “Design Sonore” n°41 (2005) 16--19"[3] N. Kubo “Types of Car Sound Quality categorized by Frequency Dynamics”, ICSV16,Krakow9