Please consider that the temperature in our lab was summerly 26°C instead of 21-23°C that we normally have during the rest of the year. Hence it's safe to discount 2 or 3 degrees from the test result.
Disk Noise Level
As the decibel scale is logarithmic, I decided not to start the graphic at 0 but at 20, just to make clear that the difference in noise level is sometimes bigger than the numbers might suggest. All three budget drives stay below 50 db(A), which is a good result. Particularly the Maxtor drive is very quiet.