In the past, we knew a truck was approaching long before we saw it. There would be a deep grumbling sound to give us plenty of advance notice. And yes, that’s still the case, but thanks to a great many innovations in and on vehicles, the interval between hearing the truck and seeing it is getting shorter and shorter, and for some engine types, it’s practically non-existent. Which raises the question: how loud or how quiet must, or may, a commercial vehicle be? To answer that question, the engineers from Daimler Trucks listen very carefully when the Mercedes-Benz trucks and buses roll by their microphones at the new acoustics measurement site in Münsingen.