Improving the Sound Quality of the Closing Sound of a Car Door
Although the closing sound of a car door is objectively not related to the intrinsic qualities of the vehicle, it is an important subjective parameter for vehicle evaluation. This closing sound can emphasize the impression of a solid, rockproof car body or can draw the attention to a rather cheap, flimsyvehicle. Several other adjectives can be used to describe the closing sound, which is certainly, often unconsciously, an element that improves or lowers the global image of the vehicle. However, this sound is hardly related to more obvious criteria of a vehicle's quality. Nowadays, there are several low cost, low class vehicles that do have an equal or even better closing sound than more expensive upper class vehicles. Indeed, it is by simple and cheap measures that this closing sound can be shaped and engineered.
Although the closing sound has only a limited duration, in this 1,8-second time period 15 mechanical events have been identified. These events are all related to the motion of the internal parts of the lock and the contacting of the door to the rubber seals. The importance of these 15 events has been investigated by means of wavelet and Sound Quality analysis. The wavelet analysis enabled the quantification of the frequency content of the individual events. By means of replaying and editing the measured sound signals the subjective importance of individual events has been established.
The average door slam has approximately 90 decibels.
(that's total dBSPL, not just the infrasonic freqs)
Studies have been done by consulting firms that make loads o dough designing door mechanisms that attenuate higher freqs and increase ULF proportionately in the spectral content of the actual event of closing a car door.
Feel free to venture a guess which is the car door slam after improvements result in a subjectively higher quality sound:
Of course, the car companies are probably just gullible and movie soundtrack listening is probably different and needs to be 10 to 20 times louder (and add all the rest of the crazy stuff that people tend to offer in these sorts of threads).