I have a 250Gb LaCie External HDD and for a while now, it has been making a crackling noise (sort of) constantly when it is in use. It isn't a clicking noise, which I understand indicates a failing drive, but it is annoying.
It has done it for a few months and it is still chugging along so I don't think so. Also, it transfers data fine. It just seems like it shouldn't be making this noise. I wonder if there are a few lose screws are something inside the enclosure.
I'm not familiar with that specific brand of drives, but if it has a fan, check that one out. It could be either the fan itself, or something loose next to it.