Thanks for your answers
I've found some accoustic noice values on the Fujitsu website, all for 100 GB HDDs:
o MHV2100AT: 24 dBA, 2.3 bels
o MHU2100AT: 25 dBA, 2.4 bels
o MHV2100AH: 28 dBA, 2.6 bels
Because of I don't know the accoustic noice values of my Hitachi HDD (where can I get them?), so I can't evaluate the given values above. Is 28 dBA loud?
For me criteria#1 is, that the HDD isn't heard in an absolutly silent room (with exception from the HDD access operation), and criteria#2 is, that the HDD isn't poor in performance. When I see the values above, I recognize the difference between a 4200 and 5400 rpm HDD. Is 28 dBA much louder as 25 dBA?
I only want to stop the permanent bothering noice from the bottom right corner