How do you gauge the build quality and safety of a new car at the showroom? Apart from physically touching the materials and panels inside the car or intensively staring at panel gaps, we Malaysians are also quite fond of the classic “slam-the-door technique” – the solid, deep thumping sound from closing the doors is the definitive mark of a well-built car, right? Well, not really, actually.

The sound that you hear from closing the doors of a brand-new BMW for example is actually engineered specifically to make you feel that way, as reported by Mel, thanks to a little something called “psychoacoustics”, which essentially means the study of the psychological, cognitive and sensory responses associated with sound.

Stanford University Centre for Computer Research in Music and Acoustics professor, Jonathan Berger explains: “One of the first things a prospective car buyer encounters is the sound of the driver’s door closing — often inside the showroom. This sound gives a subconscious sense of value.”

Berger has even put the hypotheses to test with his psychoacoustic class students, where he had them rank eight car doors from least to most expensive, just based on the sound that it makes. Respondents felt that a “low, soft thud” with an after sound of some sort (Berger gave the example of a “ker-chunk”) sounds the most premium.

The results mirroring a similar decade-long study from Purdue University, which concluded that tinny door-closing sounds give off the perception of cheap and flimsy cars. Of course, car manufacturers already know that, and thus employ a group of acoustic engineers to make the sound of their doors – among many other things – sound just right. Lexus even made a commercial for their engineered door-shutting sound.

The practice started about 10 years ago, according to the co-founder of AutoBead, James Ford, where changes in the manufacturing process thanks to more stringent safety standards changed the sounds car doors made while closing. “Engineering the right sound of a car door closing was their first opportunity to make buyers feel the car’s quality, craftsmanship and safety and to justify a premium price tag.”

To be fair though, when we say “engineer”, we don’t mean fake sounds – like engine noise – pumped into the cabin via the sound system. Manufacturers use specific combinations of soft materials such as mats or foam on the metal surfaces of the door – and each brand will have their own “blend”, so to speak – to absorb or block unwanted noise, while creating their own unique “thwump” sound.

Without these dampeners, the car door closing would sound more like two pieces of metal clanging together, which we imagine doesn’t sound like a pleasant experience at all. After that, the engineers then alter the locking mechanism to make “just the right sort of click” (see: Mercedes-AMG G 63) for the perfect after sound as explained by Berger.

So yes, your solid-sounding door is a lie, and it doesn’t directly reflect the safety and build quality of the car. Although, the fact that manufacturers put the effort to craft the sound your car makes when you slam the door is a good indication that the new car you’re planning to buy is well engineered to even the smallest details.

Make of it what you will with this new information, but I know that I probably wouldn’t be slamming on car doors the next time I walk into a dealership.

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Believes that a car is more than just numbers and facts, it's about the emotions they convey. Any car can be the right car for someone, but he'll probably pick a hot hatch over anything else.