I am always impressed by how much I don’t know about trains/model trains. Even basic stuff.
The other day I went to a steam festival. Among other things I watched the demonstration of various steam whistles blown on a manifold in a static display. I dawned on me that I had always thought that the whistles operated like an organ…with what is called a mouth, flue and labium (I Googled it just now).
Turns out that while some steam boat whistles were like that, train steam whistles create a resonation by blasting the steam column up to the inner dome or bell of the steam whistle and then it is deflected down. That much was obvious to me as soon as I saw the exhaust of all the whistles blasting in a downward direction. Various sizes and shape of the brass “bell” part give various tones, of course.
I particularly liked the Penn Central 5 tone whistle.