I already asked the grandparent, but received no response[1]. What make/model generated that profile? And how does it compare to the same measuring setup used on other units? While they may all look the same at a distance, you can find vast design differences between them when you start to look closely. It seems unlikely that they would all generate the exact same noise.

To put it another way, a car on the NASCAR circuit looks a lot like a road suitable car anyone can buy at the dealer's lot, but the sound is completely different. It pays to be specific.

[1] https://news.ycombinator.com/item?id=14174426