Yup, the Sharkoon 80mm/2000 is louder than the 120mm/1000.
80mm/1000 - very quiet, I use this cooling the hard disk
120mm/1000 - very quiet, I use this on an Ultra-120
80mm/2000 - Audible, I use these fans connected to the motherboards Q-Fan controller, either as Case/Intake fans 'or' as the CPu fan. Running at full whack you can hear these things so that why they work great with a fan-controller of some sort, totally quiet when system idle and audible when the system is under heavy load.
120mm/2000 - This is too loud for me, tried it for a few evenings but it drove me mad running at full whack and the ASUS/INTEL Q-Fan didn't slow it down?, will be installing it soon in an ASUS/nForce Q-Fan system as a cpu fan matched with an older XP-120, hopefully the nVidia chipset will be able to slow it down when the system is idle lol!