Boy, that Ellwood Haynam really had that whistle sound down!
It was a modern train sound, and now I am educated as to the difference! Love that modern chime sound, which isn’t all THAT modern, because I think I’ve been hearing it since I was a kid in the 50s, right?
Even some late model ('40s-'50s) steam locomotives carried air horns in addition to their steam whistles. Most were of the single note variety.
Steam whistles are not as efficient as air horns and consume a relatively large volume of steam when in use.
It was found that fuel and water savings were obtained by using the air horn in place of the steam whistle as the main warning device on those steam locomotives so equipped.
Here is a video of preserved Southern Pacific 4449, a streamlined steam locomotive built in 1941, arriving in Naperville, IL on a 2009 excursion run, demonstrating both her deep 3 chime whistle and her single note air horn: