Everybody's ears are sensitive to different tones and frequencies. I hear fan noise more than the average person, while the average HDD noise barely registers. I know some people that are very "in-tune" with coil whine, even when it is in a case and a fan is spinning at 1000rpm or better right next to it. All hard drives make a noise, some are irritating and some aren't. My new Seagate Barracuda(7200.14 Power of One) hard drive makes a noise unlike any I've ever heard. When it is working it makes a squelch type noise. Squelch is the best I can describe it. It's a weird noise, but not bothersome because it very rarely makes that sound because it is a storage drive for my SSD.
Again, the SSD makes absolutely no noise.....unless you are one of the few people who have been struck by lightning or shocked real good and can "hear" electrical impulses! Another thing to consider: slower hard drives have much higher access times which means when they do have to get up and go, it's as long and drawn out as possible. Laptops that have a 5400/5900 rpm drive will have to work much longer than a new 7200rpm drive which just prolongs the noise it makes. My hard drive makes that squelch noise less than a second and it's done......none of the endless hem-hawing around the old hard drives used to do.
If you are determined to not have to listen to hard drive noise, I have to say again, get you a good SSD and use an external hard drive for data storage. I promise you won't hear a peep out of that........plus on average you can expect 30min-1 hour more battery life with an SSD.