56: In favour of a sustainable world of sound

Since the dis­cov­ery of fire, noise has always been asso­ci­at­ed with human activ­i­ty. The indus­tri­al rev­o­lu­tion, with the devel­op­ment of trans­port and indus­try in par­tic­u­lar, led to an unprece­dent­ed increase in noise pol­lu­tion. The scale of noise pol­lu­tion grew through­out the 20th cen­tu­ry with the expo­nen­tial increase in the num­ber of cars and road trans­port, air and sea traf­fic and indus­try. These nui­sances, which were tol­er­at­ed as the price to pay for devel­op­ment, have grad­u­al­ly become intol­er­a­ble. Their impact on our health but also on the sur­round­ing fau­na has led the pub­lic author­i­ties to issue more strin­gent stan­dards and indus­try to adapt. How­ev­er, not all sound is noise. There are pleas­ant sounds, the song of a nightin­gale for exam­ple, and oth­ers that are unpleas­ant, such as the croak­ing of a crow or the noise of a pneu­mat­ic drill. UTC’s Acoustics and Vibra­tion team works in this con­text to reduce unwant­ed noise as much as pos­si­ble and make every day sounds more pleas­ant, par­tic­u­lar­ly in the auto­mo­tive and aero­nau­ti­cal sec­tors. But the team’s skills can also be used to pro­tect the envi­ron­ment, for exam­ple to detect the stridu­la­tions of the chafer lar­vae that threat­en the for­est of Com­piègne. In short, the team is help­ing to cre­ate a sus­tain­able sound universe.

Jean-Daniel Cha­zot is a lec­tur­er qual­i­fied to direct research and is in charge of the Acoustics and Vibra­tions for Engi­neers (UTC-AVI) pro­gramme with­in the mechan­i­cal engi­neer­ing department.

Not all sound is noise. Sounds and even vibra­tions are part of the nat­ur­al human envi­ron­ment. But ‘noise’ has tak­en on a par­tic­u­lar sig­nif­i­cance with the growth of human activity. 

«Engi­neers are not only try­ing to lim­it these nois­es but also try to improve the sounds made by every­day objects. In prac­tice, they even try to adapt the sound to the user. Acoustics is thus a major mar­ket­ing argu­ment in all sec­tors. More­over, reduc­ing vibra­tions also makes it pos­si­ble to increase the lifes­pan of equip­ment for more sus­tain­able devel­op­ment,» he says. 

How­ev­er, the role of the vibro-acoustic engi­neer is chang­ing. Why? «The evo­lu­tion and tight­en­ing of reg­u­la­tions linked to noise pol­lu­tion in order to pro­tect the con­sumer, but also the envi­ron­ment, fol­low­ing an aware­ness of the effects of noise pol­lu­tion. The WHO esti­mates that noise pol­lu­tion is the sec­ond main cause of mor­bid­i­ty – 12 000 pre­ma­ture deaths in Europe — after air pol­lu­tion. The health and envi­ron­men­tal issues of noise pol­lu­tion Jean-Daniel Cha­zot is a lec­tur­er qual­i­fied to direct research and is in charge of the Acoustics and Vibra­tions for Engi­neers (UTC-AVI) pro­gramme with­in the mechan­i­cal engi­neer­ing depart­ment. We can also cite a study by Bruit­parif which con­cludes that peo­ple in the Paris region lose 10 months of their healthy life due to noise pol­lu­tion, which caus­es stress, hyper­ten­sion, sleep dis­or­ders and car­dio­vas­cu­lar prob­lems,» empha­sizes Jean- Daniel Chazot. 

Reduc­ing these nui­sances is there­fore a major health issue for human beings but also for ecosys­tems. «For exam­ple, an Amer­i­can study shows that human activ­i­ty dou­bles the back­ground noise in 63% of nat­ur­al areas that are sup­posed to be pro­tect­ed. Nui­sances that affect the health of ani­mals, dis­turb their com­mu­ni­ca­tions and cause them to move away from their ter­ri­to­ry. Anoth­er exam­ple is the harm­ful effects of ship­ping, which dou­bles its noise lev­el every ten years, on under­wa­ter life,» he adds. 

A reduc­tion that is there­fore a major chal­lenge for vibro-acoustic engi­neers. «At UTC, we give our stu­dents a sol­id the­o­ret­i­cal and prac­ti­cal train­ing so that they can mea­sure, mod­el, under­stand and treat vibra­tions and asso­ci­at­ed acoustic emis­sions. With these dif­fer­ent skills, they can reduce nui­sances at source and treat struc­tures to reduce their acoustic radi­a­tion,» he explains. 

These prob­lems also give rise to research, very often car­ried out with indus­tri­al part­ners but also with pub­lic fund­ing from the French gov­ern­ment, the Hauts-de-France region and Europe. 

«For exam­ple, a the­sis is under­way, with the Region­al Cen­tre for Inno­va­tion and Tech­nol­o­gy Trans­fer (CRITT), on the exper­i­men­tal char­ac­ter­i­za­tion of tur­bine gen­er­at­ed noise,» he explains. 

Oth­er projects in progress? «We are cur­rent­ly work­ing with Saint-Gob­ain, as part of a the­sis on the vibroa­coustic mod­el­ling of a wind­screen. Anoth­er is under­way with Safran. The aim? To under­stand and reduce the unpleas­ant noise of elec­tric motors,» con­cludes Jean-Daniel Chazot.

Jean-Daniel Cha­zot details the nui­sances asso­ci­at­ed with the Asian hor­net, a species on the list of inva­sive alien species in Europe. A min­is­te­r­i­al the­sis is devot­ed to what has become a research topic.

This species pos­es both health and envi­ron­men­tal prob­lems. «Hor­nets are dan­ger­ous for humans; they are also dan­ger­ous for bees. This caus­es dam­age to bee­keep­ers but also to the envi­ron­ment, as bees play a major role in pol­li­na­tion,» he explains. 

What can be done to lim­it the nui­sance, espe­cial­ly since nests can often only be detect­ed in autumn when the trees lose their foliage? Jean-Daniel Cha­zot then had the idea of con­tact­ing Pedro Castil­lo from UTC-Heudi­asyc, who works on drones. «For us, we are think­ing about a drone sys­tem equipped with an acoustic anten­na that would make it pos­si­ble to fol­low a hor­net equipped with a small sound bea­con in order to locate the nests with­out wait­ing for autumn,» he says. 

What was sup­posed to be a stu­dent project even­tu­al­ly took a dif­fer­ent course. «We respond­ed to calls for projects that allowed us to ben­e­fit from a min­is­te­r­i­al the­sis on this research sub­ject, which involves, in addi­tion to Rober­val and Heudi­asyc of the UTC, the Jean-le-Rond‑d’Alembert Insti­tute of Sor­bonne Uni­ver­si­ty, «empha­sizes Jean-Daniel Chazot. 

A sub­ject that requires spe­cif­ic skills. «At the UTC, our skills relate to drones and acoustic imag­ing. As for the Insti­tut d’Alembert, it brings its exper­tise in MEMS sen­sors. What we plan to do is to attach a MEMS speak­er to a hor­net and fol­low it with a MEMS micro­phone anten­na on the drone. These are very light minia­turised sen­sors that can be installed in num­bers but with a rea­son­able addi­tion­al mass. How­ev­er, before we can do this, we will have to remove cer­tain sci­en­tif­ic and tech­no­log­i­cal bar­ri­ers, such as the dif­fi­cul­ty of track­ing a mov­ing acoustic tar­get,» he concludes.

Dectection of chafers’ larvae that have infested the forest

After two years of prepara­to­ry class­es in Arras, Camille Leblanc was admit­ted to UTC in the 3rd year of mechan­i­cal engi­neer­ing and con­tin­ues his stud­ies in the Mecha­tron­ics, Actu­a­tors, Robot­ics and Sys­tems (MARS) pro­gramme. He will start a the­sis in embed­ded acoustic imag­ing at Rober­val as of autumn 2021. 

It was fol­low­ing a CC on “Sound sig­nal pro­cess­ing” with Solène More­au, a UV that I real­ly enjoyed’, he says, that he dis­cov­ered a pas­sion for the subject. 

Lack­ing cred­its in his 4th year, he was able to bounce back by opt­ing for a project to be car­ried out between the two semes­ters in order to make up for the lack of CCs. This was a good oppor­tu­ni­ty because, at the same time, Jean-Daniel Cha­zot pro­posed an inter-semes­ter project on the study of the sig­nal emit­ted by bee­tle lar­vae threat­en­ing the for­est of Com­piègne but also else­where in Europe. «Three stu­dents applied and all three were select­ed, as the work to be done was sub­stan­tial,» he explains. 

The project itself? «We took up the work of Ms Gör­res, a Ger­man research sci­en­tist, who used a frac­tal method to detect the pres­ence of lar­vae and, above all, to quan­ti­fy it. We there­fore used her script as a start­ing point and then improved it by test­ing it on real cockchafer chirps,» con­cludes Camille Leblanc. 

Stéphane Brault is a research assis­tant at the ONF (French Nation­al Forestry Com­mis­sion), where he mon­i­tors the forests of Com­piègne and Laigue. Spe­cial­ist of ento­mol­o­gy ques­tions, he has his sights set on the chafer lar­vae that infest twothirds of the for­est sur­face, albeit with vary­ing densities. 

These lar­vae devour the roots over a peri­od of 4 years, pre­vent­ing nat­ur­al regen­er­a­tion and plant­i­ng. The idea behind the col­lab­o­ra­tion with UTC? «In ento­mol­o­gy, some species can only be deter­mined by acoustics. How­ev­er, while search­ing the sci­en­tif­ic lit­er­a­ture, I real­ized that very suc­cess­ful sci­en­tif­ic research had been car­ried out on chafer infes­ta­tions in sug­ar­cane fields in cer­tain coun­tries of the Indi­an Ocean. At the ONF, we thought that this was an avenue to explore with the UTC,’ he explains. 

Jean-Daniel Cha­zot, head of the AVI course, seized the oppor­tu­ni­ty to set up an interse­mes­ter project on the study of the sig­nal emit­ted by the lar­vae. It was too short a project for such a com­plex sub­ject. «It should be not­ed that four years pass between the lay­ing of the eggs and the ini­tial flight of the chafer. Long-term stud­ies would there­fore be nec­es­sary as part of a the­sis, for exam­ple,» he stresses. 

Espe­cial­ly as there are many obsta­cles to over­come. «One of the main ones is not hav­ing a tool for mon­i­tor­ing the insect, i.e., we are unable to say how many there are. Today, the only way we have is to make holes in the ground. How­ev­er, pop­u­la­tions can vary from 1 to 10 from one hole to anoth­er that is one metre apart,» con­cludes Stéphane Brault. 

After two years of prepara­to­ry class­es in Arras, Camille Leblanc was admit­ted to UTC in the 3rd year of mechan­i­cal engi­neer­ing and con­tin­ues his stud­ies in the Mecha­tron­ics, Actu­a­tors, Robot­ics and Sys­tems (MARS) pro­gramme. He will start a the­sis in embed­ded acoustic imag­ing at Rober­val in the fall of 2021.

Pro­fes­sor at UTC since 2012, Nico­las Dauchez is a mem­ber of the Acoustics and Vibra­tion team with­in the Rober­val lab­o­ra­to­ry. He is spe­cial­ized in the reduc­tion of noise pol­lu­tion by means of so-called «pas­sive» methods.

What does it mean in prac­tice? «Depend­ing on the con­text, we try to reduce nui­sance by using absorbent mate­ri­als that have the prop­er­ty of being porous, such as foams or fibrous mate­ri­als. In the auto­mo­tive indus­try, for exam­ple, this involves lin­ing the roof, the floor, the door lin­ings, the dash­board and also every­thing around the engine block with the appro­pri­ate mate­r­i­al. In the case of aero­nau­tics, it is a ques­tion of using a lin­ing with a dual func­tion: a ther­mal and acoustic insu­la­tion role,» he explains. 

The tight­en­ing of noise stan­dards is hav­ing an impact on a large num­ber of sec­tors. This has led to a boom in vibro-acoustics, the study of vibra­tions that gen­er­ate sound. «We are inter­est­ed in the vibra­tions of struc­tures. In the auto­mo­tive indus­try, for exam­ple, the vibra­tions of a car body are gen­er­at­ed by var­i­ous sources. In par­tic­u­lar, there are aero­dy­nam­ic vibra­tions, road vibra­tions and engine vibra­tions that can pro­duce sound both inside and out­side the vehi­cle. We will there­fore mod­el var­i­ous sit­u­a­tions and try to find ways of lim­it­ing the nui­sance, using suit­able mate­ri­als, etc.,» explains Nico­las Dauchez. To do this, the vibroa­cousti­cians use two approach­es, one ded­i­cat­ed to dig­i­tal sim­u­la­tion, the oth­er experimental. 

What is the role of dig­i­tal sim­u­la­tion? «We will devel­op mod­els to explain the observed phe­nom­e­na. In fact, in our approach, we try to com­pare mea­sure­ments with cal­cu­la­tions. If the results are con­clu­sive, we deduce that the mod­el is cor­rect and we will use it to opti­mize a num­ber of solu­tions and ver­i­fy their valid­i­ty exper­i­men­tal­ly,» he stresses. 

Exper­i­men­tal tools? «The lab is equipped with a large amount of mea­sur­ing equip­ment, such as an ane­choic cham­ber, i.e., one that does not cause an echo, in which we can car­ry out mea­sure­ments with­out any noise pol­lu­tion or acoustic res­o­nance. We also have the oppo­site. In oth­er words, a rever­ber­a­tion cham­ber with oppo­site prop­er­ties but use­ful for mea­sur­ing pow­er or sound insu­la­tion. Sev­er­al acoustic ducts allow us to study silencers and a laser vibrom­e­ter allows us to mea­sure struc­tur­al vibra­tions with­out con­tact. Final­ly, a lab­o­ra­to­ry is ded­i­cat­ed to the char­ac­ter­i­za­tion of acoustic mate­ri­als,» he explains. 

This know-how, com­bined with a grow­ing need to track down noise pol­lu­tion in a num­ber of sec­tors, has led to sev­er­al part­ner­ships with the indus­tri­al world. 

The proof? Numer­ous projects such as Ecobex, with Renault, Saint-Gob­ain, Vibratec and ESI Group, a com­pa­ny spe­cial­iz­ing in dig­i­tal sim­u­la­tion in vibro-acoustics, or Sem­pae, with Renault, ESI Group and Trèves. 

Ecobex’s objec­tive, for exam­ple? «In Europe, the method of cal­cu­lat­ing noise has been mod­i­fied to be more in line with city dri­ving, which includes accel­er­a­tion episodes, episodes at con­stant speed, etc. Stricter stan­dards have been intro­duced with the aim of ensur­ing that the noise lev­el of inter­nal com­bus­tion vehi­cles does not exceed that of elec­tric vehi­cles by 2024. The three sources of car noise are exhaust noise, engine noise and tire con­tact with the road. The idea was to sim­u­late “pass­ing” noise and to devel­op inno­v­a­tive acoustic screens by mod­el­ling the prop­er­ties of porous mate­ri­als, foams or fibres, sub­ject­ed to the ther­mos-com­pres­sion process,» explains Nico­las Dauchez. This project has result­ed in the pub­li­ca­tion of three sci­en­tif­ic articles. 

A prob­lem that con­tin­ues with the Sem­pae project launched in 2020. «This time, the idea is to place the acoustic screens — either insu­lat­ing or absorb­ing — direct­ly in con­tact with the engine to gain in mass. This gen­er­ates addi­tion­al con­straints, for exam­ple the behav­iour of the mate­r­i­al in rela­tion to the tem­per­a­ture or vibra­tions of the engine,» he concludes. 

Two devel­op­ment prospects for this theme are cur­rent­ly emerg­ing: on one hand, the use of meta­ma­te­ri­als struc­tured in such a way as to sur­pass their orig­i­nal prop­er­ties, thanks to res­o­nances or their peri­od­ic­i­ty; on the oth­er, beyond the reduc­tion of noise nui­sance, tak­ing into account the user’s sound expe­ri­ence, a step towards sound design.

Solène More­au, who has been a lec­tur­er at the UTC since 2011, is a spe­cial­ist in mea­sure­ment tech­niques in acoustics in the pres­ence of flow, in par­tic­u­lar in the aero­nau­ti­cal and auto­mo­tive sec­tors. She works, in par­tic­u­lar, on silencers made of noise-absorb­ing materials.

What is the under­ly­ing idea? «The idea is to devel­op new mea­sure­ment tech­niques to char­ac­ter­ize the prop­a­ga­tion of noise with air­flow and to study new silencers or aero­dy­nam­ic phe­nom­e­na that gen­er­ate noise. Phe­nom­e­na that com­bine acoustics and flow. We know that the pre­dom­i­nant sources of noise in air­craft, for exam­ple, are engine noise, which can be reduced by silencers, and aero­dy­nam­ic noise, she explains. 

Reduc­ing these nois­es is a major health issue, espe­cial­ly since the WHO was forced in 2018 to tight­en its thresh­olds for air­borne noise, which is con­sid­ered to be the most harm­ful to health. 

This has stim­u­lat­ed a great deal of research. A the­sis has thus enabled the devel­op­ment of a mea­sure­ment tech­nique for val­i­dat­ing acoustic imped­ance mod­els of silencer/mufflers units. 

In con­crete terms? «The acoustic imped­ance of a mate­r­i­al is what deter­mines its behav­iour. In oth­er words, its capac­i­ty to absorb sound. The numer­i­cal imped­ance mod­els devel­oped in the lit­er­a­ture have been val­i­dat­ed exper­i­men­tal­ly on our aero-acoustic bench, which can go up to a Mach num­ber of 0.25, i.e., an air flow speed of about 300 km/h, for clas­sic units or Sin­gle Degree of Free­dom Sys­tems (SDOF). These are micro-per­fo­rat­ed met­al plates with a hon­ey­comb struc­ture under­neath, which is sup­port­ed by a rigid base. This con­fig­u­ra­tion absorbs noise like that of an air­craft tur­bo­jet engine. Engine nois­es, in short, that are heard main­ly dur­ing take-off and land­ing,» she explains. 

How­ev­er, in planes, for exam­ple, it’s not only the engines that gen­er­ate noise. We also have aero­dy­nam­ic noise. In oth­er words, the noise gen­er­at­ed by an air­flow on con­tact with an obsta­cle. In this case, it’s air­craft wings. «A the­sis devot­ed to this prob­lem is cur­rent­ly under­way, with two lines of research : First­ly, to devel­op a laser mea­sure­ment tech­nique for air­flow acoustics, and sec­ond­ly to study the noise gen­er­at­ed by a flow on an air­craft wing pro­file. This is gen­er­al­ly the noise that is heard when air­craft are high in the sky. At present, we know how to describe the noise gen­er­at­ed, but we know less about the gen­er­a­tion mech­a­nisms. This is what we are going to try to under­stand,» con­cludes Solène Moreau.

Characterization of porous acoustic materials

Alexan­dre Wilkin­son did all his stud­ies at UTC. A grad­u­ate of the mechan­i­cal engi­neer­ing depart­ment (UTC-IM), major­ing in Acoustics and Vibra­tions, he start­ed a doc­tor­ate in the UTCRober­val lab­o­ra­to­ry in Octo­ber 2020 after his end-of-stud­ies engi­neer­ing intern­ship at Renault. 

The sub­ject of his the­sis? «The objec­tive of this the­sis is to char­ac­ter­ize porous engine encap­su­la­tion mate­ri­als, such as foams or fibrous mate­ri­als. This the­sis is part of SEMPAE, an indus­tri­al project that includes, in addi­tion to the UTC, Renault, the equip­ment man­u­fac­tur­er Trèves and ESI Group, which spe­cial­izes in dig­i­tal sim­u­la­tion,» he explains. 

A project ded­i­cat­ed to track­ing down noise pol­lu­tion, par­tic­u­lar­ly in motor vehi­cles. «The aim of the project is to devel­op soft­ware to sim­u­late the behav­iour of porous mate­ri­als encap­su­lat­ing a car engine and to cal­cu­late the noise radi­at­ed or, con­verse­ly, atten­u­at­ed by the use of a par­tic­u­lar mate­r­i­al. My role in the project is to char­ac­ter­ize these dif­fer­ent porous mate­ri­als, find the mod­els adapt­ed to their use and, ulti­mate­ly, mod­el their behav­iour in this soft­ware,» he explains. 

These mate­ri­als are not easy to sim­u­late and will be mod­elled in stages. «I start­ed by com­par­ing the mea­sure­ments with sim­u­la­tions using the sim­plest meth­ods, main­ly trans­fer matri­ces where we assume that we have an infi­nite plane of foam. Then we will move on to the finite ele­ment method, which con­sists of dis­cretiz­ing a space that may have a more com­plex geom­e­try, and cal­cu­lat­ing a quan­ti­ty at each point (or node) cre­at­ed,» con­cludes Alexan­dre Wilkinson.

As a spe­cial­ist in sound design, Christoph Har­bon­nier lec­tures in the UTC Design Depart­ment with­in the Mechan­i­cal Engi­neer­ing depart­ment (UTC-IM). For the past fif­teen years, he has been man­ag­ing the Audio­naute stu­dio, found­ed by the con­tem­po­rary music com­pos­er Michel Redolfi.

As a design­er and a musi­cian, it is quite nat­ur­al that Christoph Har­bon­nier became inter­est­ed in all aspects of sound. «For me, it is a ques­tion of think­ing about the tim­bre of sounds accord­ing to the con­text. With­in the frame­work of the Audio­naute stu­dio, for exam­ple, we have car­ried out sound design oper­a­tions in pub­lic trans­port, in par­tic­u­lar in the tramways of cities such as Brest, Besan­con and Nice,» he explains. 

His approach to sound design? «The most impor­tant thing is to «revis­it» the com­fort of users, par­tic­u­lar­ly in the sound con­tent. We study the his­to­ry, cul­ture and archi­tec­ture of the city close­ly in order to per­son­al­ize the sound atmos­phere cho­sen for each oper­a­tion as best we can. It’s an excit­ing but com­plex job, where we try to cre­ate a spe­cif­ic look for each sta­tion, but also to adapt the sound of the mes­sages, for exam­ple, depend­ing on whether it’s dur­ing the day, gen­er­al­ly nois­i­er, or in the evening, when it’s a ques­tion of calm­ing the pas­sen­gers. A sound pack­age that must ‘speak’ to users by com­bin­ing func­tion, com­fort and plea­sure,» he says. 

This approach some­times leads them to inter­vene upstream in the choice of audio equip­ment, for exam­ple.» The basic equip­ment of trams, whether they are made by Bom­bardier, Alstom or the Span­ish com­pa­ny CAF, is cat­a­stroph­ic in terms of acoustics and deemed “unwor­thy” of the com­fort of users. We have there­fore sys­tem­at­i­cal­ly replaced the basic loud­speak­ers with a sys­tem of small loud­speak­ers that we devel­oped with Audax, a French loud­speak­er man­u­fac­tur­er,» stress­es Christoph Harbonnier. 

This know-how is of inter­est to all the big names in the sec­tor in France: Keo­lis, Véo­lia and Trans­dev. He also tries to pass on this know-how to stu­dents as part of the UTC Acoustic Design course. This is a first for a uni­ver­si­ty of tech­nol­o­gy. «It’s a joint course for AVI and IDI stu­dents that links the acoustics and indus­tri­al vibra­tions depart­ment, which uses mea­sure­ment tools to analyse the phys­i­cal char­ac­ter­is­tics of sound, and the design depart­ment, where we design, imag­ine and cre­ate sounds,» he concludes.

Pierre-Hen­ri Dejean, an archi­tect, urban plan­ner and ergono­mist, joined the UTC in 1984. He is respon­si­ble for the Indus­tri­al Design Engi­neer­ing (IDI) programme.

His first feel­ing about sounds? «At the time, I could say that my ‘encounter’ with sound was neg­a­tive because, as an archi­tect as well as an ergono­mist, sound, in the indus­tri­al sec­tor, is asso­ci­at­ed with noise — machine noise, for exam­ple. Since then, indus­try has moved on, dri­ven by stan­dards and reg­u­la­tions,» he says. 

How­ev­er, by work­ing in the prod­uct area, he changes the way he looks at noise to sound. «I had indeed already evolved a lot by mov­ing from the world of work­ing con­di­tions in indus­try to the prod­uct field. When I arrived at UTC, I inte­grat­ed the ‘design’ course and I nat­u­ral­ly tried to inter­est the Acoustics and Vibra­tion course in the prob­lem­at­ic of the prod­uct, a field that requires think­ing about the user,» he underlines. 

How can we move from noise to sound when we know the health and envi­ron­men­tal nui­sances caused by the for­mer and the oper­a­tional inter­est of the lat­ter? «I would say that sound is inher­ent to human activ­i­ty. Wasn’t the first design­er the one who cre­at­ed the first flint-stone tool? The sounds in our envi­ron­ment con­sti­tute a very strong infor­ma­tion sys­tem. A stormy sea, for exam­ple, does not emit the same sounds as a calm sea,» he maintains. 

The role of acousti­cians for the ergono­mist and/ or sound design­er? «With acousti­cians and in par­tic­u­lar their mea­sur­ing devices and record­ing sys­tems, we will try as ergono­mists and then as design­ers to dis­tin­guish use­ful sounds from those that are use­less,» explains Pierre-Hen­ri Dejean. In con­crete terms? «We’re going to elim­i­nate non-use­ful sounds, which are con­sid­ered to be noise, for two rea­sons. The first is that they serve no pur­pose and the sec­ond is that they can inter­fere with real­ly use­ful sounds. Then we iso­late the use­ful sounds and try to see what the human being retains, whether he is aware of it, etc. We talk about acoustic intel­li­gence, which, in the case of the human being, is the most impor­tant thing. We talk about acoustic intel­li­gence, which is often a reflex. If you close a door, for exam­ple, you know, just by the sound it makes, whether it is closed or not. In a car, for exam­ple, we know from the sound alone that some­thing is wrong with the engine. Final­ly, the designer’s objec­tive is to go fur­ther: to arrive at the plea­sure sound con­fig­ured to be both use­ful and pleas­ant,» he concludes.

Le magazine

Novembre 2023 - N°61

Activité physique, nutrition & santé

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