I think you recently developed super hearing because HD's always have made a noise like that, Sata or IDE. 5400 or 7200 RPM.
I don't think we're talking about he same tone.. I've probably had 50 ATA HDs and never heard it... various noises yes, but not this. I guess from the kinds of response that most don't perceive it or that it's as annoying as it is to me..
I know exactly what you're talking about, it's rather irritating. From what I know a few SATA drives use cheaper fluid bearing motors that will make that idle irritating high pitched noise. I think most of the manufacturers have now upgraded and use more quiet and reliable FBDs.
My oldest SATA is the one which does not make the tone... all the others are effectively brand new, and they all do it. Which makers and models do not make the tone, do you know?
I can only confirm for an assortment of 2007 Raptors. I have installed Raptors from pre-2007 which do not make the noise. I asked a buddy of mine whose an engineer at Seagate, and he told me about the noisy FBDs.
FWIW I have 3 Hitachi SATA II drives in 3 comps. and I do not notice any high pitched or annoying sounds. I'm also the kind of guy that goes ape-shit if I hear a squeak or rattle in my car.