PC fan noise ratings

One thing that really bugs me about PC fan noise ratings is that they aren't standardized.

Yeah, sure, some will list a "dB" number. But that doesn't mean anything, because how it's measured isn't standardized. Decibels measure how loud something is. They don't specify how far away from the source of noise that measurement is taken; sound energy falls off proportional to the square of the distance. They don't specify where, relative to the fan, that measurement is taken, such as whether the body of a PC is in the way. They don't specify the surroundings of the fan, like whether it's in a PC or not when being measured. If the fan is variable-speed, as most present fans are, the speed of the fan isn't specified or constant across vendors. Sound level meters have different sets of weightings that they can apply to different frequencies in calculating a loudness, and which weighting they use isn't necessarily specified (though I have sometimes seen the A scale specified). A vendor doesn't have to measure that fan under the same set of conditions as other vendors, and, in fact, has an excellent incentive to not do so, to choose the most-favorable set of conditions if a consumer is going to be comparing their fans to another vendor's.

If a reviewer is going to do a roundup of fans, then they (hopefully) at least use the same methodology for all the fans they're testing, so any numbers they provide are meaningful for comparisons between fans within that one review. But I rarely see such roundups. So for a consumer, getting meaningful data about the noise a fan makes is rather difficult when trying to pick a product.