However, head movement isn't always audible. 3½" and 5¼" drives aren't
usually audible, although I've had a few very noisy 5¼ drives. And of
course SSDs are utterly silent.
I wonder how ancient drives you are using? Have there even been any mainstream 5¼ inch form factor HDDs manufactured since the Quantum Bigfoot in the 1990s? I remember those drives being quite loud indeed.