Arnaud Duval, grad­u­ate of Arts et Métiers in Angers and hold­er of a DEA in acoustics from the Uni­ver­si­ty of Le Mans, was appoint­ed the Acoustics and Inno­va­tion Direc­tor of the Trèves group in 2016. A group that adheres to the Unit­ed Nations Glob­al Com­pact project. 

Not wish­ing to con­tin­ue with a the­sis, he chose to work in indus­try and more par­tic­u­lar­ly for the auto­mo­tive sec­tor. The role of the acousti­cian? «Our job is to reduce noise. Either by act­ing direct­ly at the source or, if we can’t, by pre­vent­ing the noise from being trans­ferred to the area of the occu­pants or users of any noisy machine. Final­ly, the tools used in the auto­mo­bile indus­try can be trans­posed to the rail­ways or the aero­nau­tics indus­try, for exam­ple. How­ev­er, we do not have the same con­straints con­cern­ing fire, etc.,» he explains.

So, after sev­er­al years with an auto­mo­tive sup­pli­er, he arrived at Trèves with a pre­cise roadmap. «One of my mis­sions was to man­age both the acoustic and ther­mo­me­chan­i­cal exper­tise and the inno­va­tion plan. It was a ques­tion of struc­tur­ing inno­va­tion by set­ting up process­es, called ‘Tech­nol­o­gy Readi­ness Lev­el’, sim­i­lar to those of the aero­nau­tics indus­try,» he says.

But his role does not end there. He con­tributes to the group’s exter­nal influ­ence, notably through inter­na­tion­al con­fer­ences, and is in charge of research col­lab­o­ra­tions with aca­d­e­m­ic insti­tu­tions, includ­ing UTC. «We set up fund­ed research pro­grammes, in par­tic­u­lar with Cifre doc­tor­al the­ses. We have two per­ma­nent PhD the­ses, one of which is cur­rent­ly with UTC, and two post-doc­tor­al the­ses at the moment. With the Cifre the­ses, we are work­ing, for exam­ple, on the prob­lem of encap­su­lat­ing engines with the aim of reduc­ing noise. Indeed, by 2024, the stan­dard for exter­nal noise, which is 70 dBA today, will be reduced to 68 dBA, know­ing that we have already reduced it by two dB over the last three years. This is con­sid­er­able,» he explains. Noise reduc­tion can be achieved in two ways. «The man­u­fac­tur­ers ask us to reduce the noise at the source. So by act­ing direct­ly on the engine. This has an impact on the noise gen­er­at­ed both inside and out­side. But also to find solu­tions to reduce rolling noise, since this type of noise is becom­ing more and more pre­pon­der­ant with the devel­op­ment of elec­tric vehi­cles,» adds Arnaud Duval.

Indeed, all man­u­fac­tur­ers are faced with the same equa­tion. «Among their pri­or­i­ties, inte­ri­or acoustic com­fort comes first as a dif­fer­en­ti­at­ing ele­ment, but it is also a ques­tion of reduc­ing exte­ri­or noise for the well-being of local res­i­dents, espe­cial­ly since the «Pass By» stan­dards are becom­ing stricter. Stud­ies are cur­rent­ly being con­duct­ed on the link between these stan­dards and the real­i­ty of noise in cities. How­ev­er, Bruit­parif, which maps the sources and loca­tions of noise pol­lu­tion in the Paris region, points the fin­ger main­ly at vehi­cle horns, two-wheel­ers, lor­ries and only after that at pri­vate vehi­cles, par­tic­u­lar­ly road con­tact rolling noise,» he explains.

Hence the major chal­lenges of inno­va­tion in the mate­ri­als used by the var­i­ous play­ers work­ing on the noise prob­lem, includ­ing the Trèves group. There are two main areas of focus. «The first, which we are work­ing on, con­cerns the tran­si­tion from plas­tic tech­nolo­gies to recy­cled and recy­clable tex­tile tech­nolo­gies for under­body pan­els, mud­guards, etc. in order to reduce rolling noise with a poten­tial of 0.7 to 1 dBA. Admit­ted­ly, this may seem like a small brick, but we hope to go fur­ther. The sec­ond con­cerns the issue of road sur­faces. Bruit­parif works a lot with road sur­face man­u­fac­tur­ers. And we have observed that cer­tain sur­faces can gen­er­ate a reduc­tion in rolling noise of up to 6 dB, or even 8 dB! And if we only take the low range, on a ring road such as the Parisian periph­ery, this is gigantic!

Among the con­straints weigh­ing on the auto­mo­tive sec­tor? “The main chal­lenge for the auto­mo­tive indus­try today is to reduce emis­sions, par­tic­u­lar­ly CO2, but also the over­all envi­ron­men­tal impact through life cycle analy­ses. This, at our lev­el at Trèves, implies con­sid­er­ably increas­ing the pro­por­tion of recy­cled mate­ri­als in our prod­ucts but also ensur­ing their recy­cla­bil­i­ty at the end of their life,» he explains.

Which mate­ri­als will ulti­mate­ly be used in the car of the future? «In the frame­work of Glob­al Com­pact, a Unit­ed Nations pro­gramme to which Tri­er is a mem­ber, the group has set itself the objec­tive of achiev­ing 80% recy­cled mate­ri­als and 80% recy­clable mate­ri­als by 2027. This is ambi­tious but achiev­able, espe­cial­ly as we already have know-how in the use of recy­cled cot­ton or poly­ester fibres, for exam­ple. We are also increas­ing­ly mov­ing towards the use of nat­ur­al fibres such as linen or hemp. Most of our prod­ucts already con­tain around 70% recy­cled mate­r­i­al. Reach­ing 80% is there­fore a major chal­lenge,» con­cludes Arnaud Duval.