Are auto races really too noisy? Faced with mounting environmental pressure, the FIA (Fédération Internationale de l'Automobile) turned to CETIM* to find out by measuring the noise generated by racecars. However, the method developed, which consisted of measuring the decibels emitted by racecars as they passed through an archway equipped with microphones, came up short in terms of separating out the noise of two cars very close to each other. CETIM asked List, a CEA Tech institute, to sol ve the problem.

The researchers began by acquiring reliable data. They ran test campaigns on three go-carts equipped with microphones, accelerometers, and an embedded GPS sensor in addition to the twelve microphones on the archway. They studied more than a hundred passes through the archway with the go-carts in various positions with regard to each other. The time it took the go-carts to pass through the archway was estimated using ultrasonic measurement followed by an analysis of the overall space-time profile (the sum of individual measurements) to determine each vehicle's noise emissions, regardless of the distance between vehicles. The measurements were accurate to within less than a decibel. The "separation" algorithm, which can unambiguously identify vehicles that are too noisy, could also be used in other areas, like submarine acoustics, without major modifications.

*CETIM: Centre technique des industries mécaniques