Most hard drives today are very silent. I can't comment on external drives in particular as I have never owned one (hope to some day when storage costs go down in the future). Seagate in particular, however, is widely recognized for the quietness of its hard drives, right down to the head noise (read/write activity)
I remember when I was a young teen, I used to love certain HDD sounds. Drives that made that hollow metallic sound (like the echo from the inside of a can or something?) always drove me nuts; I loved it. I guess cause you could tell "it was working" or some mental attachment like that.
These days even with your PC tower next to you, or relatively close / on the floor it is hard to hear any kind of drive activity.. Thankfully the same is true of CD/DVD Burners now also..
My very first CD-ROM was pretty quiet, but defective for whatever reason.. I just couldn't get it to work.. It was a christmas gift too, which bummed me out.. My dad had to take it back to some store that was I think around an hour or more away.. I noticed the price of a CD-ROM/Sound Card combo had dropped significantly (I would have asked for that instead) but they told him he'd have to get the drive exchanged for another one... What the hell is wrong with getting a refund, or exchanging and then paying the difference? Fuckers.. My first sound card would have to wait... another year or two.
Anyway the drive he brought home was the devil incarnate.. I was so happy I didn't care, and I know it had something to do with my case and the screws too, but this thing was EVIL.. Some discs were ok or respectable, but most would spin up and the drive would go mmmmmmMMMRRRRRRRRRRRR, almost like listening to an electric engraver. The whole case would sometimes vibrate with it, and I would have to grab the thing and push the sides together to help quiet it down.. The good news was, I could finally buy CD-ROM games.. Of course the first one I got was ULTIMATE DOOM, hehe.. Luckily I found it on sale at Staples, complete box and papers, etc.. None of that jewel case repack shit to save $. It was only $10. I bought it and that night I didn't go to bed at all. Later I did major chores to save up and buy DOOM ][ from Best Buy for about $25 thanks to a coupon... Man those were the days
It was only an 8x drive! Unbelievable. Finally after all these years I own a DVD burner that is very quiet and gives almost no noise.. When I have the spare cash (probably have to wait for birthday $) I am going to replace it with the same drive (or a better model if available) as my brother has now. A Samsung SATA burner.. This drive is damn near SILENT even when burning at full speed.
Oh how the times have changed... My first hard drive was a MASSIVE monster that took up TWO 5.25" drive bays on my old standard IBM AT case. For a whopping 10MB of storage space....... Back then I still didn't know how to read space properly and went nuts thinking I had a 1 Gigabyte drive (It HAD to be, I mean the drive is HUGE, when most only take up one 5.25" bay!)
My grandfather soon correct me though....haha